Grigoriadou, M., Tsaganou, G., & Cavoura, T. (2005). Historical Text Comprehension Reflective Tutorial Dialogue System. Educational Technology & Society, 8 (4), 31-41.
Historical Text Comprehension Reflective Tutorial Dialogue System
Maria Grigoriadou
University of Athens, Dept. of Informatics and Telecommunications
GR-15784, Athens, Greece,
gregor@di.uoa.gr
Grammatiki Tsaganou
University of Athens, Dept. of Informatics and Telecommunications
GR-15784, Athens, Greece,
gram@di.uoa.gr
Theodora Cavoura
University of Thessaly, Dept. of Education
Argonafton & Filellinon strs, GR-38221, Volos, Greece
theokav@pre.uth.gr
ABSTRACT
The Reflective Tutorial Dialogue System (ReTuDiS) is a system for learner modelling historical text
comprehension through reflective dialogue. The system infers learners’ cognitive profiles and constructs
their learner models. Based on the learner model the system plans the appropriate --personalized for
learners-- reflective tutorial dialogue in order to promote their reflection, a fact which leads them towards
scientific thought. The system consists of two parts: (1) the Diagnosis part and (2) the Reflective Tutorial
Dialogue part. In this paper we present the dialogue strategies, tactics and plans which are used by the
dialogue part for the generation of the appropriate for learners’ reflective learning dialogues according to
their learner models. Moreover, in this paper we present the experts’ comments concerning the tutorial
dialogue during an experiment.
Keywords
Dialogue-based reflection, Interactive dialogue, Planning and Historical text comprehension
Introduction
Tutorial dialogue has many positive characteristics for promoting learning. It provides learners with a learning environment that is appropriate for the accomplishment of learning goals. It provides tutors with the opportunity of tailoring instruction to individual needs. Reflective tutorial dialogue between learner and the system about the learner’s own beliefs can make a learner model open (Kay, 2001; Paiva & Self, 1995). Interactive open learner modelling involves human learners in learning dialogues to improve learning through promoting and facilitating reflection. Advanced computer learning environments require open learner models, which promote reflection, in order to help learners overcome their learning difficulties (Bull, 1997; Bull & Nghien, 2002). Open learner models encourage learners to reflect on the domain being studied, on their own strategies for learning and on their own understanding. Towards this direction, the dialogue management, the dialogue strategies and the dialogue tactics, which mainly formulate the dialogue framework, aim at the promotion of reflection in learning (Freedman, 2000; Schultz et al., 2003; Zinn et al., 2002). Through dialogue learners defend their views to the system by collaborating, discussing and arguing the assessment, which the system has made of their knowledge and beliefs. The recently growing interest in opening learner models to learners encourages the development of tutorial dialogue systems which give learners greater responsibility and control over their learning process (Kay, 2001).
There are systems in the literature supporting student models, which are related to text comprehension. SimStudents, an integrated student model for story and equation problem solving, uses an ACT-R based cognitive model (MacLaren & Koedinger 2002). Other systems are the Empirical Assessment of Comprehension (Mathan & Koedinger 2002) and the Engines for Education (Schank & Cleary, 1994). The model of literacy comprehension (Zwaan, 1996) takes into account the predication semantics model of text comprehension and recall (Turner, 1996) and is based on the Construction-Integration model (Kintsch, 1975). The model of narrative comprehension and recall (Fletcher, 1996) is based upon Trabasso & Van den Broek’s model (Trabasso, 1985), which considers understanding of text as a process of finding (by the reader) the causal path which links text from the beginning to its end. Recently, various approaches have been proposed which involve learners in negotiating dialogues, as well as learner models which encourage learners towards inspection and modification
of the model (Dimitrova, 2002; Zapata-Riviera & Greer, 2002). Moreover, developments promoting collaborative student modeling such as SQL-Tutor (Bull, 1997), dialogue planning (Freedman, 2000; Watson, 1997), learner reflection through discussion such as StyLe-OLM (Dimitrova, 2002), mixed -initiative dialogue (McSherry, 2002), dialogue management (Freedman, 2000, Zinn et al., 2002) and tutorial dialogue (Schultz et al., 2003) have been explored. ATLAS-ANDES is a tutorial dialogue system, which uses a combination of knowledge construction dialogues and allows the generation of tutorial dialogues (Zinn et al., 2002). ScoT is a scalable, reusable, conversational tutorial dialogue system (Schultz et al., 2003).
In this paper we present ReTuDiS, a dialogue-based reflective learning system, which constructs dialogue based on the learner model for Historical Text Comprehension (Grigoriadou et al, 2003; Tsaganou et al., 2003b). First, we outline how the system bases learner’s historical text comprehension on the recognition of general cognitive categories. Applying the hybrid technique of Fuzzy-Case-Based Reasoning, the system infers learners’ cognitive profiles in the diagnosis part and constructs the learner models. In the next section we describe how the strategies of the Theory of Inquiry Teaching (Collins, 1987) are adopted in the dialogue part. We concentrate on how the appropriate tutorial dialogue is generated using the library of dialogue-parts. Moreover, in this section, we display the four- stages interactive dialogue between a learner and the system, as well as how the dialogue engages learners to reflect on their own strategies in each of these stages. Formative evaluation and results are discussed. Finally, we conclude and give our future perspectives.
ReTuDiS
ReTuDiS is a diagnosis and tutorial dialogue learner modelling system, which infers learners’ cognitive profiles of historical text comprehension (Tsaganou, 2002). ReTuDiS, based on the Theory of Inquiry Teaching (Collins, 1987), exploits cognitive profiles to construct learner models and produce appropriate for each learner tutorial dialogues. ReTuDiS consists of two parts: The Diagnosis part and the Dialogue part.
The Diagnosis part of ReTuDiS
ReTuDiS is based on MOCOHN (Model of Comprehension of Historical Narration) a pencil-and-paper diagnosis model of learner’s comprehension of historical text (Cavoura, 1994; Cavoura, 2000). Based upon the narrative approach of historical text (Ricoeur, 1983), the mental models of Johnson-Laird and Schank & Abelson’s text comprehension theory (Schank & Abelson, 1977), MOCOHN adapts Baudet & Denhière’s theory (Baudet & Denhiere, 1992) for historical text comprehension. It considers text comprehension as the attribution of meanings to causal connections between occurrences in a text. Learners compose a representation of the historical text, which contains the cognitive categories: event, state and action (Baudet & Denhiere, 1992). Learners’ arguments are based on the three cognitive categories. For the interpretation of learners’ cognitive processes learners’ discourse is analysed, in order to trace the recognition (or not) of the three cognitive categories. MOCOHN gives an explanation of the way students represent the world of history and the way their cognitive processes lead to comprehension of a historical text.
ReTuDiS system is designed to be applicable not only to historical texts but to any texts with a causal structure. The diagnosis part of ReTuDiS engages learners in an activity which includes reading comprehension of a historical text and answering question-pairs by using given alternative answers (Tsaganou et al., 2002; Tsaganou et al., 2003a). The historical text includes factors, which represent the three cognitive categories action, state and event. For every factor at least one question-pair, is submitted to the learner. The first question in the question-pair is related to the causal importance of the specific factor and a learner’s answer concerning this question is called position. The second question is related to a learner’s justification concerning the selected position and is called justification. Learners have to study all the text to comprehend it, to compare each factor with the others and then select answers. The purpose of the activity is to train learners in procedural knowledge. The types of cognitive processes learners expected to activate correspond to Bloom’s taxonomies: (1) remember, (2) understand: learners compare factors, explain them, draw logical conclusions using the presented material and (3) analyse: learners distinguish important from unimportant factors (Anderson et al., 2001). Learners’ answers are used for diagnosing their historical text comprehension. The learner has to use the given alternative answers, in order to express his position for certain historical issues and support it by selecting a justification. Alternative answers concerning position and justification are classified as valid, towards-valid or non-valid as they are depicted in Tables 1 and 2. Figure 1 depicts a historical text concerning five different factors of the outbreak of the French Revolution. It also depicts question-pair number 1 and alternative answers with (non-visible by the learner) characterizations. In the historical text, one factor represents the cognitive category event, another one
the cognitive category state and three others the cognitive category action. For example, for question-pair 1 the alternative answers a1 and b3 are non-valid, a2, b1 and b4 are towards-valid, whereas a3 and b2 are valid.
Figure 1: A screenshot of ReTuDiS
Table 1. Classification of answers concerning position
position answers valid learners attribute minimum importance to an event and a state and maximum or medium importance
to an action
towards-valid learners attribute medium importance to events and states
non-valid learners attribute maximum importance to an event or minimum importance to an action
Table 2. Classification of answers concerning justification
justification answers valid learners grounded their answers on scientific historical thought
experiential : learners used their own experience or sentiment to strengthen their position
quantity: learners used quantitative criteria to strengthen their position continuity: learners perceived the world as
continuous
towards-valid learners based their answers on the common sense schemas of experience, quantity, continuity and attitudes, which
means learners are towards acquiring scientific thought attitudes: learners expressed positive or negative
values (for example good, bad) towards the historical
events
non-valid learners gave cyclic answers based on the questions posed (non-scientific thought)
For every question-pair the combination of a learner’s position and the corresponding justification constitute the learner’s argument . An argument is defined as complete, when both position and justification are valid . Otherwise the argument is non-complete. Possible values of argument completeness are: c omplete, almost complete, intermediate, nearly incomplete and incomplete. The expert defines the different degrees of argument completeness. Argument completeness --which is associated with the recognition (or not) of an instance of a cognitive category-- is used as a vehicle for revealing the degree of recognition (or not) of the corresponding cognitive category. In case an argument is non-complete , it means that there is a contradiction between position and justification for the corresponding question-pair.
The Diagnosis part of the system, using IF…THEN rules, which incorporate the description of expert knowledge concerning learner answers to question-pairs, infers the argument completeness of all the learner arguments. Learners’ behaviour, represented by the characterisations of positions, justifications and arguments, constitute the problem description of the corresponding case. A case is viewed as a set of attributes where the characterisations are the problem description and the cognitive profile is the solution. Representative cases constitute a case-base. Using the technique of Fuzzy-Case-Based Reasoning the system handles case adaptation --by comparing the similarity values of argument completeness between cases—in order to infer learners’ cognitive profiles (Tsaganou et al., 2003b). Based on the hypothesis that similar problems have similar solutions the system estimates the degree to which a case is similar to a case stored in the case-base, using a fuzzy k-nn algorithm. The system adopts the cognitive profile of the most similar case. This technique achieves the right balance between the hard to acquire expert knowledge and the more easily acquired knowledge in the form of cases (Watson, 1997).
Learners’ cognitive profile is measured by the degree of argument completeness and reflects the degree of recognition of all the cognitive categories: event, state and action while expressing learners’ difficulties, if any, in thinking scientifically. Cognitive profiles represent a learner classification scheme and correspond to the main levels of scientific (historical) thought. The main categories of cognitive profiles are: (1) Low profiles for learners who seem to encounter serious difficulties, (2) Intermediate for learners who seem to encounter some difficulties on which the reflective dialogue focuses in order to help learners overcome them and (3) High for learners who seem to have no learning difficulties. The target group the system focuses upon includes learners for whom the system diagnoses contradictions between a position and a justification for a given question-pair, a fact which means that they encounter difficulties in thinking scientifically.
The Dialogue part of ReTuDiS
ReTuDiS aims at constructing reflective dialogue concerning learners’ contradictions in their answers. The learning outcomes are summarized as follows. Learners must be able:
1.to recognize the three cognitive categories state event and action
2.to appraise a factor in the historical text which corresponds to the cognitive category action as the most
important cause rather than to a state or event.
3.to meet reflective dialogue and to construct coherent arguments, which means without contradictions
between a position and its justification.
The underlying theory beyond the tutorial Dialogue part of ReTuDiS is the Theory of Inquiry Teaching (Collins, 1983). This theory is prescribed as a theory for the use of discovery and inquiry approach in learning. Many of its strategies are intended to develop higher thought processes rather than content-specific know1edge. Questions provide the focus and direction for the instruction through reflective tutorial dialogue. Learners formulate hypotheses based on observation of varied cases (examples), in order to force greater depth of processing of the new knowledge. In ReTuDiS the following tactics are adopted in dialogue part as instruction tools:
1.Selecting Positive and Negative Examples. When a learner considers an accidental event like “the heavy
winter of 1989” as more important than an action, the system presents positive paradigm cases like “an earthquake”.
2.Selecting Counterexamples. If a learner forms a hypothesis which is not completely true, the system will
often select a case, which satisfies the learner’s hypothesis but violates the hypothesized prediction. For example, the learner considers “living conditions of the 3rd class before 1789” as the most important cause.
The system’s counterexample can be: “whenever people’s living conditions are bad, do we have a revolution?”
3.Generating Hypothetical Cases: generate hypothetical cases in order to force learner’s reasoning about
situations that are hard to reproduce naturally.
4.Forming Hypotheses: try to make the learner predict how a dependent variable varies with one or more
independent variables or factors. The system generates the hypothesis that “if the heavy winter of 1789 had not happened, would the outbreak of the French Revolution have happened?” in order to make the learner reason about it.
5.Testing Hypotheses. Once learners have formulated a hypothesis, the system wants them to figure out how
to test the hypothesis.
6.Tracing Consequences to a Contradiction. System often traces the implications of a learner’s answer to a
contradiction with some other belief the learner holds.
The dialogue part of ReTuDiS uses information included in a case: characterizations of the learner’s positions, justifications and arguments, the learner’s cognitive profile inferred by the diagnosis part and the dialogue strategy. In order to generate the appropriate dialogue in response to learners’ feedback, the system assesses the contradictions within the learner’s arguments in the corresponding case. Depending on the characterizations of positions and justifications the dialogue part activates the appropriate for each learner sequence of dialogue-parts, and by using the dialogue plan, dynamically constructs the individualized learning dialogue. Dialogues are appropriate to each learner’s learning difficulties, as they appear according to his/her learner model.
Dialogue Strategies
Tutorial strategies are methods for constructing an initial plan for reflective dialogue. ReTuDiS is designed to allow for reflecting tutoring. In order to construct an initial overall tutoring plan, the system uses information from the annotated case of a learner's performance in a comprehension activity concerning a historical text. The initial tutoring plan can be dynamically revised during the tutorial dialogue. ReTuDiS presently has three main strategies for taking instructional decisions and constructing the initial tutorial plan. The system tries to find out if there is a contradiction between characterisations of a position and a justification. One of the following strategies can be applied:
1.Strategy 1: the system selects the factor, which the learner considers as the most important of all others. The
Tutorial dialogue begins with a discussion about this factor.
2.Strategy 2: the system sorts learner’s argument characterizations in a list according to decreasing degree of
argument completeness. The reflective dialogue begins with a discussion about the factor for which the learner seems to face minor contradictions. The system generates the sequence of dialogue-parts for this factor (initial plan). Then the system prepares the next sequence of dialogue-parts, based on the results of the previous.
3.Strategy 3: the system examines every factor, in order to find out if there is a contradiction between
characterisations of position and justification (for example, valid position and non-valid or close-to-valid justification and the contrary) and ignores the factors for which there is no contradiction, either because both position and justification are valid or because both position and justification are non-valid.
Dialogue-parts Library
The system has at its disposal the dialogue-parts’ library (Tables 3, 4), which contains general dialogue-parts and specific dialogue-parts of different types. Each general dialogue-part is seen as a reusable component for the construction of the dialogue between a learner and the system and is independent of the historical text. Each specific dialogue-part is seen as a reusable component, which is dependent upon the specific historical text. Specific dialogue-parts which learners use in the dialogue are the alternative answers. Specific dialogue-parts, which the system uses in the dialogue, follow dialogue tactics and are designed to remedy a particular learning difficulty.
Table 3. Dialogue-parts library- General parts
types of dialogue-parts dialogue-parts
comparisons the most important cause, important cause, less important cause
position or justification
valid, towards-valid, non-valid
descriptions
argument descriptions complete, almost complete, intermediate, nearly incomplete, incomplete
experience, quantity, continuity, views, cyclic
explanations explain, don’t explain
intentions insist, don’t insist
selections happened, not happened, yes indeed, no I don’t believe, yes I’d like, no I don’t like contradictions contradictory to, not contradictory to
The dialogue part of ReTuDiS generates the appropriate to each learner tutorial dialogue using the library of general dialogue-parts (Table 3).
Table 4: Dialogue-parts library- Specific parts
types of dialogue-parts dialogue-parts
factors the living conditions of the 3rd class,
the heavy winter of 1789,
the financial development during the decade 1930,
the convergence of the general classes by the King,
bourgeois and 3rd class jointly claim for constitution
learner’s argumentations expressing:
scientific thought the living conditions were the same for many years
experience the 3rd class felt unfairly dealt with,
despite the financial development 3rd class continued to be displeased,
the delegates of the bourgeois are indignant towards the King and the nobility
3rd class was numerous,
quantity the
the more the people the more the possibilities for success, due to the heavy
winter the life of a large number of people became harder,
the financial development increased the number of bourgeois
continuity the heavy winter made the poverty worse,
bourgeois and 3rd class share the same goals
views due to the heavy winter the rural crop was bad,
people work and the nobility enjoy
cyclic thought 3rd class lead a hard life
system argumentations expressing:
examples the heavy winter or an earthquake are accidental events
counterexamples whenever the living conditions of people are, bad do we have a revolution?
whenever a social part is unfairly dealt with or is displeased, do we have a
revolution?
is a revolution always provoked by numerous social parts?
generation of hypothesis form the hypothesis that the living conditions as a cause for the French
Revolution didn’t exist.
Dialogue Plan
Dialogue is generated in 4 stages (Figure 2). A sequence of dialogue-parts, each based on the results of the previous stage, constructs the dialogue plan (Table 5).
STAGE 1: The system makes learners aware of the general framework of the assessment results, that is whether learners are correct or not, and encourages them to take their first decision to participate in the discussion. Dialogue-part S1D1 is generated by the system, in case learners want the system to explain them the differences between their answers and the system concerning an argument. Dialogue-part S1D2 is generated in case learners do not want the system to explain them the dialogue concerning their argument. Dialogue is thus terminated. STAGE 2: The system uses qualitative criteria to indicate the points where there are contradictions between learners’ position and their justification. Dialogue-parts S2D1 to S2D5 are generated by the system according to the different combinations of learners’ responses, which correspond to different degrees of argument completeness and are related to one of the five factors in the historical text. When dialogue-part S2D5 is generated, the system responds appreciatively as regards learners’ abilities and encourages them to return to stage 1 and continue with the next argument.
STAGE 3: Each learner’s decision triggers the system to use the appropriate individualized tactics. The Dialogue-part S3D1 is generated, in case learners insist on their answer and dialogue-part S3D2, in case they do not insist, which means that they recognize their contradiction and change their reasoning.
STAGE 4: The system discusses, justifies itself and argues with learners over their contradictions. The appropriate dialogue-parts S4D1, S4D2 and S4D3 are generated, in case learners insist on position, on justification or on both respectively. The actions of the system have to be driven towards eliminating the contradiction. The elimination will only be possible when learners themselves remove the contradiction and are thus able to construct a more coherent argument. At the end, the system encourages learner to try again to read
the historical text and answer the questions, so that it can have a second opportunity to reassess learners. In this way, learners are involved in the diagnosis process and are expected to change their model.
Figure 2: Dialogue stages
Table 5: Dialogue Plan
1 System: Your answers concerning the …(factor) indicate that you consider it as … (comparison) for the French Revolution. Your argument is characterized …(description). Do you want the system to… or to….? (selection)
Learner: I’d like to …(explanation)
2 System: You asked the system to explain. Your answers concerning the …(factor) consist of your position and your justification. Your position is that the …(factor) were… (comparison) for the French Revolution. This is a …(description) position. Your justification for that position is that the …(alternative answer). This is a …(characterization) justification. Your position on the …(factor) is …(contradiction) your justification. That is why your argument is characterized …(description). What do you intent to do now?... or ….( intention)
Learner: I …(selection) on my position that the …(factor).… (comparison).
3 System: You …(decision) on your position.Let’s consider that the …(factor) as a cause for the French Revolution didn’t exist. Do you believe that the outbreak of the French revolution would have happened?
Learner: I believe that the outbreak of the French revolution would have …(selection).
System: But the outbreak of the French revolution has happened. So, what is your logical conclusion?
Learner: The …(factor)…(comparison)
4 System: Would y ou like to try to answer again?....(selection)
Dialogue Tactics
The following dialogue example (Table 6) illustrates the interaction concerning question-pair 1. The learner has given non-valid position and valid justification, which correspond to answers a1 and b2 of Figure 1 and result in an intermediate argument of the category state. ReTuDiS uses dialogue tactics to support tutorial interactions. For example, in turn 3, the tactics: selection of counterexamples and generation of hypothesis are used. The learner considers the “living conditions of the 3rd class before 1789” as the most important cause. The tutor’s counterexample can be “whenever the living conditions of people are bad, do we have a revolution”? In order to make the learner reason about it the tutor generates the hypothesis that: “if the heavy winter of 1989 had not happened, would the outbreak of the French Revolution has happened”?
Table 6: Dialogue example in 4 turns concerning an argument
1 System:Your answers concerning the LIVING CONDITIONS indicate that you consider it as THE MOST IMPORTANT CAUSE for the French Revolution. Your argument is characterized INTERMEDIATE. Do you want the system to EXPLAIN or to CONTINUE?
Learner: EXPLAIN
2 System: You asked the system to explain. Your answers concerning the LIVING CONDITIONS consist of your position and your justification. Your position is that the LIVING CONDITIONS were THE MOST IMPORTANT CAUSE for the French Revolution. This is a NON-VALID position. Your justification for that position is that the LIVING CONDITIONS WERE THE SAME FOR MANY YEARS. This is a VALID justification.
Your position on the LIVING CONDITIONS is CONTRADICTORY TO your justification. That is why your argument is characterized INTERMEDIATE. What do you intent to do now? INSIST or NOT INSIST. Learner: I INSIST on my position that the LIVING CONDITIONS ARE THE MOST IMPORTANT CAUSE.
3 System: You INSIST on your position.Let’s consider that the LIVING CONDITIONS as a cause for the French Revolution didn’t exist. Do you believe that the outbreak of the French revolution would have happened? Learner: I believe that the outbreak of the French revolution would NOT have HAPPENED.
System: But the outbreak of the French revolution has happened. So, what is your logical conclusion? Learner: T he LIVING CONDITIONS ARE NOT THE MOST IMPORTANT CAUSE
4 System: Would y ou like to try to answer again?
Formative Evaluation
Formative evaluation was conducted as part of the development cycle of the system using the web-based version of ReTuDiS (https://www.wendangku.net/doc/8d17821937.html,/kostas74/History/first.asp) and with the participation of human experts. Their comments were recorded and an interview at the end clarified uncovered aspects. Evaluation aimed at further revisions, modifications and improvements (Mark & Greer, 1993; Mitrovic et al., 2002) and focused on indicating problems with dialogue coherence, suitability of dialogue tactics and strategies appropriate for planning effective diagnostic dialogues. The experts were given explanations about the aims of ReTuDiS and asked to explore a variety of potential situations envisaging learner’s behaviour who would discuss his domain knowledge with the system.
Figure 3. Changes in the cognitive profiles
ReTuDiS recorded learners’ answers and inferred their cognitive profiles, taking into account their argument completeness for all stated arguments, before and after the application of the reflective dialogue. Figure 3 presents learners’ cognitive profiles before and after the application of the reflective dialogue. The horizontal axis shows the 20 learners (S1 to S20) classified from lower to higher cognitive profiles. The vertical axis shows cognitive profiles {very low, very low+, low, low+, nearly low, nearly low+, below intermediate, below intermediate+, above intermediate, above intermediate+, nearly high, nearly high+, high, high+ and very high}, which correspond to {1,2,3,4,5,6,7,8,9,10,11,12,13,14}. It is worth noticing that most of the learners with a high degree of argument completeness indicated improvement in their learner models. For example, in the group of learners S6, S7, S8 and S9 with a low cognitive profile, only S7 improved his cognitive profile by one level, whereas in the group of S10 and S11, with low+ cognitive profile, S10 improved his cognitive profile by one level and S11 by two levels.
In general, dialogue planning appears suitable for organising dialogue which meets the requirements of dialogue-based interactive and reflective learning. The dialogue tactics in ReTuDiS have been considered adequate in respect to maintaining local focus of the dialogue. Few problems with the current implementation have been identified, e.g. occasional repetitions of statements and questions about already made claims have occurred. A richer domain knowledge base could lead to higher chances of obtaining adequate dialogue tactics.
Conclusions and Future Plans
In this work we have presented and evaluated ReTuDiS. Based on diagnostic results, the dialogue part engages learners in learning dialogues according to appropriate dialogue strategies and tactics. Dialogue indicates contradictions amidst learners’ answers and discusses with learners, in order to help them eliminate their contradictions. Dialogue promotes learners’ reflection and helps them become aware of their reasoning process and construct more coherent arguments while leading them towards scientific thought. The application perspectives of this dialogue-based interactive and reflective learning environment aim at individualized learning, by activating the appropriate to a learner interactive dialogue with the system. There are apparent educational benefits of the system in that it can help learners change their reasoning.
The research contribution of ReTuDiS, in contrast to related systems (Cavoura, 2000, Fletcher, 1996), consists in its computer-based nature for learner modeling comprehension of historical text basing comprehension on the recognition of general cognitive categories. Another innovation of ReTuDiS is the use of the hybrid technique of Fuzzy-Case-Based Reasoning in the diagnosis part for the educational purposes of diagnosis of historical text comprehension (case construction, definition of similarity measures). Moreover, innovation is the application of the Theory of Inquiry Teaching and the construction of the dialogue part (general dialogue-parts which are reusable for any new historical text, specific dialogue-parts, dialogue tactics, strategies and plans) for personalized reflective learning. The complexity of the application of a new text in ReTuDiS consists in the selection by the expert of a text with a causal structure, the definition of the factors in order to have them correspond to the cognitive categories, the construction of the appropriate question-pairs with alternative answers, the enrichment of the case base with new cases, the definition of the similarity values and the formulation of the specific reflective dialogue-parts, which are not reusable as the general are. The evaluation results are encouraging for the educational impact of the system on learners and for future work. In our future plans we foresee further research into the application of ReTuDiS to new historical texts and to technical text comprehension. Lastly, an authoring tool for the application of a new text in ReTuDiS is still under construction. References
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名词解释(2) 1、理论人类学与应用人类学之关联 举各民族物质上行为各种形态而比较他们异同”的名为“比较民族学”, 即今天所说的理论民族学, 它偏重于研究多个民族的共同发展规律。(蔡元培) 应用人类学:应用人类学是近几十年新兴起的一门人类学分支学科。它与自然科学、社会科学相结合,运用人类学的理论与社会调查的方法,着重研究现代社会结构和人民的社会生活规律。对农业与工业,农村与城市,医药与保健,环境破坏与环境保护,遗传工程进行应用研究,提出对策,应用人类学渗透到各个学科领域、社会生产的各个方面,应用范围极为广泛,已冲破自然科学和社会科学界线,进行科学间合作,协同研究。可分为结构人类学、人类工程学、医学人类学、老年人类学、分类人类学、经济人类学、人口人类学、教育人类学、空间人类学等分支学科。 2、人类学南派与北派的比较 20世纪上半叶中国人类学兼收并蓄了欧美人类学的种种学术流派,成为一个多元的学术体系。到30年代,中国人类学已形成三种具有地区特色的风格,呈华东、华南和华北三足鼎立之势。其中,受社会人类学与文化人类学影响的“北派”与“南派”,分别以燕京大学与“中央研究院”为中心形成自己的圈子。 “北派”受功能学派影响较大,偏重于一般社会科学。关注深入的民族志研究(社区调查),重视比较不同社会中人类的不同生活方式,研究并阐释各种社会现象及其发展规律;其最重要的特色在于汉人社区研究。强调社区研究方法的运用,以田野调查的实际资料和分析研究为拳头产品,通过和国外学者的交流与对话,在国际人类学界影响较大。 “南派”与历史学派关系深厚,偏向于人文学,注重物质文化与跨民族关系研究,注意力在文化研究,而非规律或原理、原则的寻求。强调以族群文化为研究对象,着重搜集传统风俗与历史源流的内容,明确提出要以人类学材料来补充历史记载不足的看法。在实地调查中,偏向于民族志描述。他们开展的田野调查数量最多、面积最广,质量上乘。 两派在经验资料与理论知识的积累方面,分别都有各自独到的开拓。 3、社会调查与社会学调查之关联(事实与理论) 社会调查是指:政府或个人组织对社会间事件的调查。如民生、物价、治安、政府公信力等领域。 社会学调查指:通过社会调查所得的结果与不同组织或个人调查结果相比较,了解两方或多方意见共同研究。 4、经济文化类型理论的主要内涵是什么? 新中国建立后,苏维埃学派对我国的民族学的影响体现在三个方面,分别是原始社会研究、经济文化类型和民族定义与识别。所谓经济文化类型,乃指“一定的经济和文化特点的综合体,它在历史上形成于处在相似的社会经济水平,并居住在同样自然地理条件下的不同民族中”。林耀华等后来将之修改表述为“居住在相似的生态环境之下,并操持相同生计方式的各民族在历史上形成的具有共同经济文化特点的综合体”。 这一理论的深刻意义表现在两方面。首先,它为世界范围内的民族共同体的分类提供了一个有效的分析框架。因为同样的经济文化类型可以独立出现在远隔千里而又无直接交往的民族中,这种超越地域性的特征使它与语言的发生学分类法以及社会形态分类法等一样,都成为民族学家认识五彩缤纷的民族文化的科学工具。 其次,依经济文化类型理论来研究中国的民族分布格局形成原因,使我们能够科学地认识汉族与诸少数民族的共生关系。
一、人类学研究定义、内涵、对象、结构 人类学定义:人类学是运用实地考察的手段比较研究各民族文化和社会的综合学科。广义的人类学涵盖了民族学、民俗学、考古学、语言学、体质人类学等多种学科。 人类学目标:通过不同社会与文化的比较,以及通过人类文化变迁历史的研究,概括出人类行为的原理、原则及人类文化变迁的一般规律,是人类学的最高目标。 人类学一词来自于希腊文中的(人)和(科学)。人类学一词最早出现于1501年,当时专指人的体质方面的研究。作为一门独立的学科,人类学形成于19世纪下半叶,至今才100多年的时间。它被称为“在科学中历史最短、抱负最大”的“研究人类的科学”。英国人类学家爱德华·泰勒1887年出版的《原始文化》一书是人类学学科正式诞生的标志。 人类学研究对象——文化的特质 文化是共享的,是外在的,可研究性;文化是可习得的;文化是象征的,建基于符号的;文化是整合的广义人类学四个主要的分支: 体质(生物)人类学、考古人类学、语言人类学、文化人类学(或称社会人类学、民族学狭义人类学则仅指文化人类学或社会人类学、民族学。 文化的结构(四层次说) a物态文化层:由人类加工自然创制的各种器物,即“物化的知识力量”构成。物态文化以满足人类最基本的生存需要——衣、食、住、行。 b制度文化层:由人类在社会实践中建立的各种社会规范、社会组织构成。 c行为文化层:由人类在社会实践,尤其是在人际交往中约定俗称的习惯性定势构成。 d心态文化层:由人类社会实践和意识活动中长期熏陶化育出来的价值观念、审美情趣、思维方式等构成。这是文化的核心部分。 二、人类学的基本观点(学科观) (一)整体论也称整体观 局部与整体间有关系;局部与其他部分有关系,分三个维度理解: A是共时性维度,整体内各个要素之间的关系,各个要素与整体之间的关系。 B是历时性维度 C是生理——心理学维度,研究人类学者与对象之间的互动关系。 (二)文化相对论 任何一种文化都必须依据它所依赖的文化结构,以及它所属的价值系统的关系来判断和解释由于每一种文化都是一个独立的体系,不同文化的传统和价值体系是无法比较的,每一种文化都只能按其自身的标准和价值观念来进行判断。 核心:衡量文化标准在该文化内部,不能以本文化的标准去衡量他文化 (三)文化普同观 人类学的核心命题是人性一致,人性需求一致,但解决此需求的手段具有多样性。可以称之为普同性。 我们特别强调整个人类是一个统一的物种,分享着一个世界,要解决相似的问题。因此,我们不能因为强调文化差异而忽视了这个道理。 (四)自观与他观(主位与客位) 自观又称“本位方法”或“文化主位研究方法”。主位方法是站在被调查对象的角度,用他们自己的观点去解释他们的文化。即用本地人(文化持有者的内部眼界)的眼光来努力理解文化。 他观又称“非位方法”或“文化客位研究方法”。客位方法是站在局外立场,用调查者所持的一般观点去解释所看到的文化。即从学者自己的文化价值观出发去研究文化。 三、人类学的研究方法
疏水阀的正确安装指南 疏水阀安装是否合适,对疏水阀的正常工作和设备的生产效率都有直接影响。安装疏水阀必须按正规安装要求、才能使疏水阀和设备达到最佳工作效率。 1. 在安装疏水阀之前一定要用带压蒸汽吹扫管道,清除管道中的杂物。 2. 疏水阀前应安装过滤器,确保疏水阀不受管道杂物的堵塞,定期清理过滤器。 3. 疏水阀前后要安装阀门,方便疏水阀随时检修。 4. 凝结水流向要与疏水阀安装箭头标志一致。 5. 疏水阀应安装在设备出口的最低处,及时排出凝结水,避免管道产生汽阻。 6. 如果设备的最低处没有位置安装疏水阀,应在出水口最低位置加个反水弯头(凝结水提升接头),把凝结水位提升后再装疏水阀,以免产生汽阻。 7. 疏水阀的出水管不应浸在水里。(如果浸在水里,应在弯曲处钻个孔,破坏真空,防止沙土回吸。) 8. 机械型疏水阀要水平安装。 9. 蒸汽疏水阀不要串联安装。 10. 每台设备应该各自安装疏水阀。 11. 热静力型疏水阀前需要有一米以上不保温的过冷管,其它形式疏水阀应尽量靠近设备。 12. 滚筒式烘干(带虹吸管型)设备选用疏水阀时请注明:选用带防汽阻装置的疏水阀,避免设备产生汽锁。 13. 疏水阀后如有凝结水回收,疏水阀出水管应从回收总管的上面接入总管,减少背压,防止回流。 14. 疏水阀后如有凝结水回收,不同压力等级的管线要分开回收。 15. 疏水阀后凝结水回收总管不能爬坡,会增加疏水阀的背压。 16. 疏水阀后凝结水进入回收总管前要安装止回阀,防止凝结水回流。 17. 在蒸汽管道上装疏水阀,主管道要设一个接近主管道半径的凝结水集水井,再用小管引至疏水阀。 18. 机械型疏水阀长期不用,要卸下排污螺丝把里面的水放掉,以防冰冻。 19. 发现疏水阀跑汽,要及时排污和清理过滤网,根据实际使用情况勤检查,遇有故障随时修理。每年至少要检修一次,清除里面的杂质。 疏水阀在整个蒸汽系统中被认为是个小配件,但对系统工作和经济运行影响很大,所以疏水阀的维护和检修也是至关重要的,只有充分重视疏水阀在生产上的重要作用。勤检修,使疏水阀经常处在良好的工作状态下,才能保证达到最佳节能效果和提高经济效益。 疏水阀的正确选型条件 1. 疏水阀的疏水量: 选用疏水阀时,必须按设备每小时的耗汽量乘以选用倍率2-3倍为最大凝结水量,来选择疏水阀的排水量。才能保证疏水阀在开车时能尽快排出凝结水,迅速提高加热设备的温度。疏水阀排放能量不够,会造成凝结水不能及时排出,降低加热设备的热效率。(当蒸汽加热设备刚开始送汽时,设备是冷的,内部充满空气,需要疏水阀把空气迅速排出,再排大量低温凝结水,使设备逐渐热起来,然后设备进入正常工作状态。由于开车时,大量空气和低温凝结水,较低的入口压力,使疏水阀超负荷运行,此时疏水阀要求比正常工作时的排水量大,
人类学研究 一、人类学(Anthyopological)的研究对象与目的 研究对象: 1、人(man)——生物人organism、文化人cultrate[k?lt??'rɑ:ti]、社会人 2、文化——人所创造的文化(Culture)包括物质文化(包括受人活动影响的生态环境)、精神文化和制度文化 3、广义具象——包括体质人类学(人体学)、考古学(史前学)、语言学、文化(社会)人类学 狭义具象——包括社会人类学、文化人类学、民族学 4、各国的本土特征不同:(英美)(欧洲) 狭义具象: 北美:文化人类学 英国:社会人类学 欧洲:民族学 因此,文化人类学、社会人类学、民族学只是各国的称呼不同,其研究对象和内容是一样的。即: 文化人类学==社会人类学==民族学 体质人类学==人体学 史前学==史前考古学 中国——先后受到欧洲和北美的影响,学科名称和术语使用一直没能统一。各种划分出入较大。 1)学科分类上:一度将人类学划归生物学。1992年,人类学被划为民族学下,成为其七个二级学科之一。后经修订,人类学又被划归社会学之下,成为社会学的二级学科。其中一些独立学科被打散在不同一级学科之下。不同称呼但内容相同的学科被划分在不同学科之下。如:民族学仍然为一级学科文化人类学放在民族学的括住内。 2)误解也比较多。如:民族学被等同为“民族研究”、少数民族研究。汉人社会研究则被拉入社会学之中。 3)公众形象与认知度非常低。 中国长期把人类学等同于“古人类学”。古人类学主要研究从猿到人的进化。这个印象与我们中国50年来知识谱系的规定有关。人类学还给外界一种接近于“ 考古学”的形象。似乎只是对古物或原始的东西感兴趣,有一种好古主义的心态。这恐怕来自以前中国人类学的“南派”(蔡元培),他们上个世纪30-40年代,以中研院为中心,做古语言、古文化、古民族研究。考古学家张光直在哈佛大学担任过人类学系主任,因而考古成了中国人类学的一种公众形象。人类学的第三种形象可能是“少数民族的原始社会形态研究”,这也有一定的历史依据和学科依据。人类学的这三种形象,不能说是公众对于人类学的歪曲。可对行内人来说,我们所做的,与人们印象中的,还是有所不同。 对人类学的认知也比较低,不仅不被公众认知,也不为大学、学者认知。 4)学科内部缺乏共同学术语言和价值观,至今尚未形成一套大家公认的基本阅读书目,缺少共同关注的概念体系。 究其原因有两点:一是,历史原因。学科命名实际上也是一种秩序构建。人类学被介绍进中国就形成了当时中国的学科秩序。以民族学(欧洲大陆)、文化人类学(美国)或社会人类学(英国)的名称进入中国的人类学,形成了不同学术特点的南派与北派。新中国建
疏水阀安装是否合适,对疏水阀的正常工作 和设备的生产效率都有直接有影响。安装疏水阀必须按正规安装要求、才能使疏水阀和设备达到最佳工作效率。 1、在安装疏水阀之前一定要用带压蒸汽吹扫管道,清除管道中的杂物。 2、疏水阀前应安装过滤器,确保疏水阀不受管道杂物的堵塞,定期清理过滤器。 3、疏水阀前后要安装阀门,方便疏水阀随时捡修。 4、凝结水流向要与疏水阀安装箭头标志一致。 5、疏水阀应安装在设备出口的最低处,及时排出凝结水,避免管道产生汽阻。 6、如果设备的最低处没有位置安装疏水阀,应在出水口最低位置加个反水弯(凝结水提升接头),把凝结水位提升后再装疏水阀,以免产生汽阻。 7、疏水阀的出水管不应浸在水里。(如果浸在水里,应在弯曲处钻个孔,破坏真空,防止沙土回吸。) 8、机械型疏水阀要水平安装。 9、蒸汽疏水阀不要串联安装。 10、每台设备应该各自安装疏水阀。 11、热静力型疏水阀前需要有一米以上不保温的过冷管,其它形式疏水阀应尽量靠近设备。 12、滚筒式烘干(带虹吸管型)设备选用疏水阀时请注明:选用带防汽阻装置的疏水阀,避免设备产生汽锁。 13、疏水阀后如有凝结水回收,疏水阀出水管应从回收总管的上面接入总管,减少背压,防止回流。 14、疏水阀后如有凝结水回收,不同压力等级的管线要分开回收。 15、疏水阀后凝结水回收总管不能爬坡,会增加疏水阀的背压。 16、疏水阀后凝结水进入回收总管前要安装止回阀,防止凝结水回流。 17、在蒸汽管道上装疏水阀,主管道要设一个接近主管道半径的凝结水集水井,然后再用小管引至疏水阀。 18、机械型疏水阀长期不用,要卸下排污螺丝把里面的水放掉,以防冰冻。 19、发现疏水阀跑汽,要及时排污和清理过滤网,根据实际使用情况勤检查,遇有故障随时修理。每年至少要检修一次,清除里面的杂质 疏水阀在整个蒸汽系统中被认为是个小配件,但对系统工作和经济运行影响很大,所以疏水阀的维护和检修也是至关重要的,只有充分重视疏水阀在生产上的重要作用。勤检修,使疏水阀经常处在良好的工作状态下,才能保证达到最佳节能效果和提高经济效益。
蒸汽疏水阀选型及蒸汽管道疏水量的计算 上海沪工阀门厂(集团)有限公司2010-06-10 摘要:介绍蒸汽疏水阀的类别及原理,对选型、安装进行一些探讨并提出了过热蒸汽管道、湿蒸汽管道的经常疏水量及启动疏水童的计算公式。 关健词:蒸汽疏水阀;疏水量;疏水阀选型 1 前言 蒸汽疏水阀是一种能自动从蒸汽管道和蒸汽用汽设备中排除凝结水和其他不凝结气体,并阻止蒸汽泄漏的阀门。它能保证各种加热工艺设备及管线所需要温度和热量并使之正常工作。蒸汽疏水阀动作正常与否,影响着蒸汽使用设备的性能、效率和寿命。据测算供热系统节能改造中,更新性能优良的蒸汽疏水阀其费用仅占系统改造总投资的7.5%,而节约能源量可占系统总节能量的30%。 以下对疏水阀的选型、安装方式及蒸汽疏水量的计算进行一些探讨。 2 蒸汽疏水阀的类别及原理 疏水阀按动作原理分类主要有:浮球型疏水阀、热静力型疏水阀、热动力型疏水阀、倒置桶型疏水阀等。 2.1 浮球型疏水阀 浮球型疏水阀包括一个浮球和波纹管元件。自由浮球式疏水阀是利用阿基米德浮力原理,使浮球随体腔内液面的升降而升降,从而打开或关闭阀座排水孔形成排水阻汽动作。浮球型疏水阀对排放容量和工作压力广泛适应,但不推荐用于有可能发生水锤的系统中。 这类阀的特点是:适用于大排量,体积较大;使用时若超出蒸汽疏水阀的设计压力,阀门则不能打开;在寒冷地区,为了防止蒸汽疏水阀内部的凝结水冻结,必须进行保温。 浮球型疏水阀的故障主要是关闭故障,浮球可能损坏或下沉,不能保持在开的位置。 2.2 热静力型疏水阀 热静力型蒸汽疏水阀是靠蒸汽和冷却的凝结水和空气之间的温差来工作的。蒸汽增加热静力元件内部的压力,使疏水阀关闭。凝结水和不凝结气体在集水管中积存,温度开始下
蒸汽疏水阀的安装要点和注意事项蒸汽疏水阀安装是否合适,对疏水阀的正常工作和设备的生产效率都有直接有影响。疏水阀的使用效果有20%的原因归结安装的质量。疏水阀作为压力管道元件,杭州瓦特节能工程有限公司认为必须是由资质的安装人员严格按正规安装要求安装疏水阀、才能使疏水阀和设备达到最佳工作效率。 疏水阀在安装前需要仔细核对型号、口径、压差、温度、压力、连接等级和标准,建立现场吊牌和疏水阀位号相结合的数据统计,以方便疏水阀运行的管理和维修。 瓦特疏水阀在出厂前必须经过承压测试和密封性测试,如果可以提供功能性测试。并提供厂家提供的一对一的试验报告或合格证书。 对于有特殊要求的疏水阀比如要求材料证书、焊接检测证书、垫片材质证明、铸件炉批号等在安装前需核对后方可安装。 1、在蒸汽管道试压时,应将疏水阀拆下,用短管代替,至少要将疏水阀前后手动阀关闭隔离。在使用疏水阀之前一定要用带压蒸汽吹扫管道,清除管道中的杂物。 2、疏水阀前应安装过滤器,确保疏水阀不受管道杂物的堵塞,定期清理过滤器。即使疏水阀自带过滤器,建议还是增加外置过滤器,过滤器采用0.5-1mm的孔径,太细压降大,太粗起不到作用。 3、疏水阀应安装在设备出口的最低处,及时排出凝结水,避免管道产生汽阻。但下降管设置集污段,避免杂质直接进入疏水阀。 4、凝结水流向要与疏水阀安装箭头标志一致。对于机械型疏水阀安装要安装厂家的安装方位。 5、疏水阀前后要安装阀门,方便疏水阀随时捡修。 6、如果设备的最低处没有位置安装疏水阀,应在出水口最低位置加个反水弯(凝结水提升接头),把凝结水位提升后再装疏水阀,以免产生汽阻。 7、疏水阀的出水管不应浸在水里。(如果浸在水里,应在弯曲处钻个孔,破坏真空,防止沙土回吸。) 8、对于有可能产生汽锁的疏水阀,要在疏水阀顶部安装平衡管。 9、蒸汽疏水阀不要串联安装。对于排空能力不好的疏水阀可以并联热静力型排空阀。 10、每台设备应该各自安装疏水阀。不能群集疏水。 11、热静力型疏水阀前需要根据过冷度有至少一米以上不保温的过冷管,其它形式疏水阀应尽量靠近设备。 12、滚筒式烘干(带虹吸管型)设备选用疏水阀时请注明:选用带防汽阻装置的疏水阀,避免设备产生汽锁。 13、疏水阀后如有凝结水回收,疏水阀出水管应从回收总管的上面接入总管,减少背压,防止回流。 14、疏水阀后如有凝结水回收,不同压力等级的管线要分开回收。 15、疏水阀后凝结水回收总管不能爬坡,会增加疏水阀的背压。 16、疏水阀后凝结水进入回收总管前要安装止回阀,防止凝结水回流。热动力疏水阀后的止回阀
人类学在中国的发展 计算机科学与技术专业 石建华 学号:2008241068 中国人类学自从19世纪末20世纪初从西方引介进来,至今已经走过100年的历程了。20世纪5年代之后我国出现的人类学研究机构中不少是从已有的社会学或者民族学研究机构中析分出来,这其中最有代表性的是1992年原北京大学社会学所改名为社会学人类学研究所。特别值得注意的是,为了尽快改变人类学学科建设相对滞后的局面,在费孝通等老一辈人类学学者的推动下,从90年代后期开始北京大学社会学人类学所先后独自或者与国内的厦门大学等其他几所高校的人类学研究机构联合,连续举办了五届人类学高级研讨班,有力地推进了人类学的发展。 虽然90年代之后,随着80年代留学西方国家的新一代社会学年轻学者的陆续学成归国,他们中有一部分人开始重视使用统计学的方法(特别是SPSS、统计软件包)开展社会调查研究,但是与此同时,“运用西方人类学方法和其他定性研究方法进行的研究也不断增加”。特别是一些本土培养的年轻的社会学和人类学学者,他们似乎更能熟练地运用人类学的研究方法来研究中国社会。有的学者认为,人类学的学科理念和研究范式有助于研究者加深对被研究对象的理解和认识,部分学者不满足于单纯的理论学术研究,他们试图利用“人类学的知识、概念和策略来解决人类的社会、经济和技术性的问题”,
借以提高人类社会的福祉,这样就出现了应用人类学。而此时,人们也发现人类学在处理某些社会问题上有其独到的策略和方法,人类学家因之享有“解决麻烦的能手”的声誉。况且现在的人类学家也普遍意识到,人类学虽然一直标榜自己是研究“人类的科学”,可是以往的人类学所关注的只是小型的非西方社区,因此有必要重构人类学的研究视野,把整个人类社会都纳入研究的范畴。与此同时,其他学科包括社会学、经济学都发现人类学学科研究所具有的独特视角有助于人们认识这些学科自身所意识不到的问题。人类学因之而开辟了另一片新天地。 遗憾的是,在中国目前的人类学界,真正从事“应用人类学”研究的学者还很少。这在客观上又限制了这门学科的进一步发展。从另一个层面来说,作为一个文化非常多元的社会,中国正在经历的急剧的现代化社会变迁为人类学的学科发展提供了难得的历史机遇,也为社会学和人类学的密切结合提供了一个天然的研究场景。针对中国人类学学科建设相对滞后于社会学的事实,人类学应该主动积极地融入对社会主流的变迁趋势的研究,以扩大其学科影响力。由于人类学惯于应用定性研究方法来研究小规模的社区,而中国目前仍然是一个传统的乡土社会和现代的城市社会相互并存的典型二元结构社会,事实证明,要研究中国乡土社会,使用定性研究方式更为合适。实际上,人类学的实地调查研究方法不仅为农村社会学者,而且也被其他学科比如农村政治学者、历史人类学者所广泛采用。当然,这并不意味着目前中国人类学者就完全停留在自己学科的领地里,陶醉于本学科的
疏水器的正确选择及安装使用 王国兴 (扬子石油化工设计院) [内容摘要]本文论述了疏水器的工作原理与分类,总结探讨了疏水器的正确选择及正确安装使用,并结合扬子石化公司的情况,提出了关于疏水器采购、节能管理的建议。对疏水器的选用、安装、管理等有一定的参考价值。 [关键词]疏水器选择安装使用 一、前言 自从产业革命以来,蒸汽已被广泛地应用在各工业部门,特别 在石化、化工、纺织、轻工、电力等行业,都大量地使用蒸汽。及时排除蒸汽系统中的凝结水、减少蒸汽的泄漏;提高蒸汽使用设备的热效率等问题。得到了各部门的普遍重视,蒸汽疏水器就是解决这些问题的主要装置。疏水器也称疏水阀,也称自动排液器,它是用在蒸汽加热设备或蒸汽输送管网上,起自动阻汽排水作用的装置。疏水器的正确选择、安装使用直接影响到蒸汽系统的安全运行和节能工作的好坏。 扬子石化公司是具有十七套大型石油化工装置的国家特大型企业,其蒸汽用热设备众多,式样各异。各种类型的蒸汽用热设备和蒸汽管网,对它们所需的蒸汽疏水系统——疏水器的要求也就不同。任何一种型式和种类的疏水器都不是万能的,因此为了选择和安装使用合适的疏水器,以满足用汽设备和蒸汽管网对疏水器的要求,首先必须了解疏水器的分类与工作原理。 二、疏水器的分类与工作原理 疏水器按工作原理一般可分为三种类型:机械型、热静力型、 热动力型。详见表1。
扬子石化公司目前共有疏水器约24000个,其中烯烃厂3400个,芳烃厂5500个。采用的疏水器型式有自由浮球式、倒吊桶式、双金属式、膜盒式、孔板式等。 三、疏水器的正确选择 选择疏水器时,不能单纯从最大排放量选择,应特别注意:“绝 不允许只根据管径大小来套用疏水器”。而必须根据疏水器选择原则并结合凝结水系统的具体情况来选用。一般情况下,应按以下三个方面选用。 3.1 首先根据加热设备和对排出凝结水的要求,选择确定疏水器的型式。 对于要有最快的加热速度,加热温度控制要求严的加热设备,需保持在加热设备中不能积存凝结水,只要有水就得排,则选择能排饱和水的机械型疏水器为最好。因为它是有水就排的疏水器,能及时消除设备中因积水造成的不良后果,迅速提高和保证设备所要求的加热效率。 对于有较大的受热面,对加热速度、加热温度控制要求不严的加热设备,可以允许积水,如:蒸汽采暖疏水、工艺伴热管线疏水等。则应选用热静力型疏水器为最好。 对于中低压蒸汽输送管道,管道中产生的凝结水必须迅速完全排除,否则易造成水击事故。蒸汽中含水率提高,使蒸汽的温度降低,满足不了用汽设备工艺要求。因此,中低压蒸汽输送管道选用机械型疏水器为最好。 总之,必须根据加热设备和用途,对疏水器型式进行合理选择。详见表2。 3.2 其次根据用汽设备的最高工作压力、最高工作温度,确定疏水器的公称压力、阀体材质;确定疏水器的连接方式、安装方式等。
人类学概论名词解释 第一章人类学要义 一、人类学 人类学的英文anthropology源于希腊语“人的学问”的复合含义。在人类学的发轫期,它关注人在自然界的位置、人的体质特征、人类和其他动物的差别,以及人类进化与变异的机制、人的体质同文化的联结性关系。人类学很早就具有跨学科考察的特征。 二、文化 最初的culture源自拉丁文“耕耘种植”之意;中世纪晚期欧洲,culture逐渐指道德完美与心智或艺术成就;18世纪欧洲,文化的集合意义强调了精神观念领域的内向性理想主义的推崇。Culture的原初概念在亚洲传播译介以日本为早,他们选择汉字“文化”对应西文中culture的同义语,意指不动用权力或刑罚而是依靠文德进行教化。汉语“文化”这一术语带有人类学启蒙、觉悟和日后濡化的精神意义和教化方式的意义。到了19世纪和20世纪初,culture成了人类学最核心概念,它的复合含义更为复杂起来。 泰勒对文化整体性的看法是:“文化……是一个复合的整体,它包括知识、信仰、艺术、道德、法律、风俗以及作为社会成员的人所获得的其他任何能力和习惯。”马林诺斯基首创功能主义的文化理论,认为“一种特质的功能,就在于满足该群体成员的基本需要和次生需要。”格尔兹“将文化视为一种象征体系”,其考察象征符号的目的是寻求该符号是如何模塑社会行动者看待、感觉和思考这个世界的,以及探索其意义并加以阐释。后现代主义又将文化转换为一个“建构性”的过程,文化的展示是形成文化的核心行为之一,也是被称作“文化的环程”的关键点,如果意义是因互动而成,那么我们的文化便具有“被分享的意义”,于是在文化的展示中,说者和听者、作者和读者都处在同一个“文化的环程”之中,而参与者之间的差异及权力因素促进了文化交流。许多重要的人类学阶段性理论和方法在某种意义上说就是文化观察的理论和方法。 三、田野工作 田野工作是人类学的首要方法和途径,田野工作强调对地方族群日常生活的直接加入,其经验性调查的特征通常是:1、学会当地的语言;2、不少于一个年度周期的居住时间;3、采纳参与观察的方法。
第一章人类学要义 1、什么是人类学? 人类学(Anthropology)源自于希腊语,含义是“人的学问”。然而,人类学的具体内涵,必须要放到它所发生和发展的具体学科进程中来理解。早期的人类学关注人论哲学的讨论和人的生物特性的研究,而到了19、20世纪,“文化”的研究成为了人类学的核心主题。基于今日现有的知识上考察人类学的内涵,可以说:人类学是关于人的学问,这包括所有时代和所有地方的人,包括人的体质特征和文化创造。人类学通常采取“田野调查”的研究方法,对文化中的“他者”进行全面的考察,基于考察撰写“民族志”,用来对不同的文化进行跨文化比较研究,最终展示人类文化的多样性和人类生活方式的多种可能性,或者试图找到具有普遍意义的社会文化理论。 2、试解释文化和culture的含义。 英文中culture一词源自拉丁语,本意是“耕耘/种植”。这不仅指“种植庄稼,饲养家畜”,也含有“照料家庭,培育道德”之意。后来,culture一词逐渐指心灵道德或艺术修养的成就和状态。这里强调culture是与nature(自然)区别开的人的创造。 在现代语境中,中文“文化”一词首先可以作为culture翻译成中文时的对等词来理解。中国传统上,有“文明以止,人文也。观乎天文,以察时变。观乎人文,以化成天下。”可以看出,作为“人的创造”的culture,中文里含义相同的应该是“人文”。“文化”一词,在传统上具有“用…人文?来教化”之意,这与culture本来的动词性含义是相通的。中文里“文化”更强调“人文”的教化方式。 3、说明跨文化比较的方法及其前提条件。 跨文化比较(cross-cultural comparison)是人类学家在对从世界上不同民族获得的经验材料进行比较的基础上,验证理论假设,发现人类行为的共性与差异,以实现理论概括或发现某种通则的方法。 跨文化比较的前提,是承认文化具有多样性、整体性和相对性的特征。而且,人类社会各种不同生活方式具有一定的稳定性,即尽管各地区的社会与文化存在差异,然而他们总会有共同的可供分析的单元与要素。还需相信,“通过习得当地人的语言,民族志工作者能够在一定程度上达到对当地文化的理解,同时承认存在着超越文化和语言界限的客观现实”。 根据黄树民的归类,人类学比较法的主要操作模式大致有三:隐含式的比较法、两元文化比较法和多元文化比较法。 4、简单概括一下人类学的四个分支学科。 人类学的四大分支学科包括:体质/生物人类学(Physical or Biological Anthropology)、考古人类学(Anthropological Archaeology)、语言人类学(Linguistic Anthropology)和文化人类学(Cultural Anthropology)或民族学(Ethnology)。 体质/生物人类学研究古今人类在自然界中生存的生物性基础,特别是人类体质特征进化和变异的过程和机制,以及人类生物性与文化的关系。 考古人类学的研究对象是人类社会的过去。它是对人类活动遗留下来的物质和非物质文化遗产进行研究,通过跨时空的文化连续性的考察,来理解人类本身。 语言人类学认为语言既是一种社会工具,也是一种文化实践。它主要研究人类世界各地语言的使用,及语言和文化的关系。
疏水器也称疏水阀或是汽水分离器(Steam Trap),它用在蒸汽加热设备或蒸汽输送管网上,是起自动阻汽排水作用的装置。选择合适的疏水阀,可使蒸汽加热设备达到最高工作效率。 自从产业革命以来,蒸汽已被广泛地应用在各工业部门,特别在石化、化工、纺织、轻工、电力等行业,都大量地使用蒸汽。及时排除蒸汽系统中的凝结水、减少蒸汽的泄漏;提高蒸汽使用设备的热效率等问题。得到了各部门的普遍重视,蒸汽疏水器就是解决这些问题的主要装置。疏水器的正确选择、安装使用直接影响到蒸汽系统的安全运行和节能工作的好坏。蒸汽中的凝结水和空气是影响热量交换和管道通过能力的有害物质,排除它们能提高用汽设备的效率,节约蒸汽、降低燃料消耗。 疏水器的分类及工作原理 疏水阀的品种很多,各有不同的性能。选用疏水阀时,首先应选其特性能满足蒸汽加热设备的最佳运行,然后才考虑其他客观条件,这样选择你所需要的疏水阀才是正确和有效的。 疏水阀要能“识别”蒸汽和凝结水,才能起到阻汽排水作用。“识别”蒸汽和凝结水基于三个原理:密度差、温度差和相变。于是就根据三个原理制造出三种类型的疏水阀:分类为机械型、热静力型、热动力型。 一、机械型疏水阀: 机械型也称浮子型,是利用凝结水与蒸汽的密度差,通过凝结水液位变化,使浮子升降带动阀瓣开启或关闭,达到阻汽排水目的。机械型疏水阀的过冷度小,不受工作压力和温度变化的影响,有水即排,加热设备里不存水,能使加热设备达到最佳换热效率。最大背压率为80%,工作质量高,是生产工艺加热设备最理想的疏水阀。 机械型疏水阀有自由浮球式、自由半浮球式、杠杆浮球式、倒吊桶式等。 Float trap with thermostatic air vent 1. 自由浮球式疏水阀: 自由浮球式疏水阀的结构简单,内部只有一个活动部件精细研磨的不锈钢空心浮球,既是浮子又是启闭件,无易损零件,使用寿命很长。 2. 自由半浮球式疏水阀:
文化人类学是研究人与文化的科学,或者说是从文化的角度研究人的科学。 美国学者霍尔姆斯首先提出文化人类学这个概念。 在美国称文化人类学,在英国称社会人类学,在欧洲大陆特别是德国称为民族学。 人类学的奠基者:拉菲托《美洲野蛮人风俗与远古风俗之比较》 古典进化论学派 这是文化人类学史上第一个流派,是文化人类学成为一门独立学科诞生的标志,盛行于19世纪60年代至90年代,成熟的标志在于E.B.泰勒的《原始文化》和摩尔根的《古代社会》古典进化论学派认为文化进化的动力:心性一致,即人类心里一致说,人们都朝一个地方想。古典进化论学派很好地解释了文化的多样性,但是它却把文化的差异性简单地解释为发展阶段的不同,从而为文化歧视甚至是种族歧视埋下了理论种子。 古典进化论学派产生的背景:一,早期的人类学知识的积累和研究组织的建立; 二,殖民贸易的发展,产生了人们研究异种族、异文化的需要, 也扩大了人们的研究视阈; 三,思想根源在于进化论理论的提出:达尔文生物进化论,斯 宾塞社会进化论。 泰勒:英国文化人类学的奠基人,第一个给文化和宗教下定义之人,第一个主张采用统计法进行人类学研究的人。《原始文化》、《论研究制度的方法:对婚姻和继承法的 应用》 进化论观点:人类社会属于自然界的一部分,人类社会的发展也跟自然界一样,是通过不断进化而发展的;人类社会的发展是有规律可循的;人类文化发展的各个阶段是 相继相承的。 宗教理论:明确了什么是宗教:一切对于神灵的信仰;探讨了宗教的起源和产生:万物有灵(全部宗教史的基础)。 婚姻家庭理论:“回避”习俗与居住模式:从妻居到从夫居;命名制度:亲从子称;继嗣制度;产翁制:由母系向父系转变;婚俗:抢婚和外婚制。 人类学研究方法:比较法(分类比较)、残存法(残留的风俗习惯)、统计法 摩尔根:美国文化人类学的奠基人,对易洛魁部落联盟的研究,首次使用问卷调查法研究人类学,首创用亲属称谓来研究家族制度。《古代社会》、《人类家庭的血亲和姻 亲制度》 原始社会分期理论:根据生产力(生产工具)的发展确定:蒙昧时代,野蛮时代,文明时代。氏族制度的发现:原始社会的基本单位;以血缘关系为基础;氏族、胞族、部落、部落联盟是一次发展的几个阶段,最终形成民族。 家庭史的研究:首次从亲属称谓制度来研究家庭和家族制度;家庭发展:“血缘”家庭,伙婚制家庭(普纳路亚),偶婚制家庭,父权制/母权制家庭,专偶制家庭。其他学者:德国人类学之父:巴斯蒂安:人类心里一致说 瑞士的巴霍芬:母权论,标志着家庭史研究的开始 英国的麦克伦南:内外婚姻制度:母权制先于外婚制 英国的卢伯克:第一个提出残存法思想;宗教阶段理论 英国的弗雷泽:首创“社会人类学”一词;《金枝》:关于人类智力发展连续性和 进步性的理论:人智力发展经历了巫术阶段、宗教阶段、科学阶段 传播论学派 产生于19世纪末的传播论学派认为人类文化发展归根结底在于文化的传播与借用,而非独
管道布置中疏水阀的安装使用 如何正确安装疏水阀 疏水阀安装是否合适,对疏水阀的正常工作和设备的生产效率都有直 接有影响。安装疏水阀必须按正规安装要求、才能使疏水阀和设备达 到最佳工作效率。 1、在安装疏水阀之前一定要用带压蒸汽吹扫管道,清除管道中的杂物。 2、疏水阀前应安装过滤器,确保疏水阀不受管道杂物的堵塞,定期清 理过滤器。 3、疏水阀前后要安装阀门,方便疏水阀随时捡修。 4、凝结水流向要与疏水阀安装箭头标志一致。 5、疏水阀应安装在设备出口的最低处,及时排出凝结水,避免管道产 生汽阻。 6、如果设备的最低处没有位置安装疏水阀,应在出水口最低位置加个 反水弯(凝结水提升接头),把凝结水位提升后再装疏水阀,以免产生 汽阻。 7、疏水阀的出水管不应浸在水里。(如果浸在水里,应在弯曲处钻个孔,破坏真空,防止沙土回吸。) 8、机械型疏水阀要水平安装。 9、蒸汽疏水阀不要串联安装。 10、每台设备应该各自安装疏水阀。 11、热静力型疏水阀前需要有一米以上不保温的过冷管,其它形式疏 水阀应尽量靠近设备。 12、滚筒式烘干(带虹吸管型)设备选用疏水阀时请注明:选用带防汽 阻装置的疏水阀,避免设备产生汽锁。
13、疏水阀后如有凝结水回收,疏水阀出水管应从回收总管的上面接 入总管,减少背压,防止回流。 14、疏水阀后如有凝结水回收,不同压力等级的管线要分开回收。 15、疏水阀后凝结水回收总管不能爬坡,会增加疏水阀的背压。 16、疏水阀后凝结水进入回收总管前要安装止回阀,防止凝结水回流。 17、在蒸汽管道上装疏水阀,主管道要设一个接近主管道半径的凝结 水集水井,然后再用小管引至疏水阀。 18、机械型疏水阀长期不用,要卸下排污螺丝把里面的水 放掉,以防冰冻。 19、发现疏水阀跑汽,要及时排污和清理过滤网,根据实际使用情况 勤检查,遇有故障随时修理。每年至少要检修一次,清除里面的杂质。疏水阀在整个蒸汽系统中被认为是个小配件,但对系统工作和经济运 行影响很大,所以疏水阀的维护和检修也是至关重要的,只有充分重 视疏水阀在生产上的重要作用。勤检修,使疏水阀经常处在良好的工 作状态下,才能保证达到最佳节能效果和提高经济效益。
人类学学科及其研究对象 目录 一、人类学的定义和研究对象 Anthropology=人类学 全面研究人及其文化的学科 体质/生物性 社会与文化 语言 历史范畴 二、人类学的四大传统分支 体质人类学 古人类学:人的出现及进化 现代人类的生物性差异 考古学 史前考古学:研究文字系统出现之前的社会 历史考古学: 语言学 研究语言与文化相互关系的学科 社会/文化人类学(民族学) 文化人类学:研究人类社会中的行为、信仰、习惯和社会组织的科学。 关于“文化”:生计、社会制度、观念意识形态(宗教信仰)、感情等。 关于“社会”:结构、组织、关系及活动 文化与社会的关系:可视为人类两个同等重要且密不可分的系统的统一体。(格尔茨) 应用人类学 三、人类学的基本原则及研究方法 基本原则 普同论:世界上现存所有的人类都是同一属性,任何一人群都不比其他人群更为进化。 全貌论:给出一个“局内的”关于社会文化的全貌图景。 整合论:强调事物之间的关联性,整体性。 适应论:人类和受周围环境的影响和制约(即人类的生存在于适应环境)。 文化相对论:每一种文化都有其独创性和充分价值,一切文化都是相对的,平等的。 三、人类学的基本原则及研究方法 人类学研究者的位置 主位(emic)与客位(etic) :主位指披调查者自己对事物的看法、分类和解释;客位指调查人员等外来者对事物的看法、分类和解释。对同一事物,两者看法可以截然不同。
人类学者:不干预,不干扰研究对象的事务和生活;不给对方带来危害;客观公正地记录,反映情况;田野调查时论文的源泉。等等。 三、人类学的基本原则及研究方法 研究方法(以民族志为例) 文献收集整理、梳理——对所研究的人、地和问题有一个总体的先期认识。 田野调查 调查前的准备:资料、调查提纲、调查工具、人员组织等 调查中:原则、道德、调查提纲、方法 调查后整理及编撰 撰写论文(或专著) 回到田野(人类学的应用与实践) ——如此反复。 四、人类学者 要求: 身体健壮、甘于寂寞、受过专业训练、操守学科道德、心绪平静。 工作地点:研究机构、田野 挑战: 长期异地作业、需要适应不同的生活和工作环境,任何条件下工作,有时会有危险。 收获: 耐心、与不同人及环境全天候打交道的能力、较为全面和缜密的思维能力、对人和文化的宽容和理解。 未来的实践者 五、非专业者的素养要求 一定的训练 一定的意识 一定的能力 一定的准备 六、人类学分支学科 经济人类学 生态人类学 语言人类学 宗教人类学 教育人类学 历史人类学 医学人类学 影视人类学 都市人类学 应用人类学 等等等等……
疏水阀安装方法 疏水阀安装是否合适,对疏水阀的正常工作和设备的生产效率都有直接有影响。安装疏水阀必须按正规安装要求、才能使疏水阀和设备达到最佳工作效率。 疏水阀是用于蒸汽管网及设备中,能自动排出凝结水、空气及其它不凝结气体,并阻水蒸汽泄漏的阀门。当使用和利用蒸汽的设备只需要蒸汽,在这种设备内肯定会产生凝结水,凝结水则成为有害的流体,同时还混入了空气和其他不可凝气体,成为引起设备产生故障和降低性能的原因。在这种情况下,疏水阀最重要的功能有以下三个方面:(1)能迅速排除产生的凝结水。(2)防止蒸汽泄漏。(3)排除空气及其他不可凝气体。 1、在安装疏水阀之前一定要用带压蒸汽吹扫管道,清除管道中的杂物。 2、疏水阀前应安装过滤器,确保疏水阀不受管道杂物的堵塞,定期清理过滤器。 3、疏水阀前后要安装阀门,方便疏水阀随时捡修。 4、凝结水流向要与疏水阀安装箭头标志一致。 5、疏水阀应安装在设备出口的最低处,及时排出凝结水,避免管道产生汽阻。 6、如果设备的最低处没有位置安装疏水阀,应在出水口最低位置加个反水弯(凝结水提升接头),把凝结水位提升后再装疏水阀,以免产生汽阻。 7、疏水阀的出水管不应浸在水里。(如果浸在水里,应在弯曲处钻个孔,破坏真空,防止沙土回吸。) 8、机械型疏水阀要水平安装。 9、蒸汽疏水阀不要串联安装。 10、每台设备应该各自安装疏水阀。 11、热静力型疏水阀前需要有一米以上不保温的过冷管,其它形式疏水阀应尽量靠近设备。 12、滚筒式烘干(带虹吸管型)设备选用疏水阀时请注明:选用带防汽阻装置的疏水阀,避免设备产生汽锁。
13、疏水阀后如有凝结水回收,疏水阀出水管应从回收总管的上面接入总管,减少背压,防止回流。 14、疏水阀后如有凝结水回收,不同压力等级的管线要分开回收。 15、疏水阀后凝结水回收总管不能爬坡,会增加疏水阀的背压。 16、疏水阀后凝结水进入回收总管前要安装止回阀,防止凝结水回流。 17、在蒸汽管道上装疏水阀,主管道要设一个接近主管道半径的凝结水集水井,然后再用小管引至疏水阀。 18、机械型疏水阀长期不用,要卸下排污螺丝把里面的水放掉,以防冰冻。 19、发现疏水阀跑汽,要及时排污和清理过滤网,根据实际使用情况勤检查,遇有故障随时修理。每年至少要检修一次,清除里面的杂质。 疏水阀在整个蒸汽系统中被认为是个小配件,但对系统工作和经济运行影响很大,所以疏水阀的维护和检修也是至关重要的,只有充分重视疏水阀在生产上的重要作用。勤检修,使疏水阀经常处在良好的工作状态下,才能保证达到最佳节能效果和提高经济效益。
发展研究:人类学的历程 杨小柳 提要:本文评述了自上世纪70、80年代,人类学发展研究兴起以来的研究成果,认为,人类学发展研究以本土知识为基点和主题,并致力于处理发展中涉及的权力关系,其中大体可以分出三大潮流:一是采用福柯式的话语分析手段解构发展;二是立足于本土知识研究,倡导自下而上的参与发展模式; 三是继续和延伸发展的话语分析,证明并展现发展实践中存在着的多种发展话语。第一类研究带来的强大批评力量令人类学在发展面前束手无策,而后两类研究的兴起则旨在缓解前一类研究带来的发展话语的解构。西方人类学发展研究的成果为中国相关研究的开展奠定了良好的基础,更为中国人类学者留下了诸多有待研究的空间。 关键词:发展 人类学 本土知识 权力 一、过程:发展、发展人类学和发展的人类学 发展(develop)一词至17世纪才正式出现在英语中,在此之前的词形是disvelop,本意为打开、展开;18世纪时,这个词为新兴的生物学所用,用以指涉人类心智的发展,因而与进化(ev olution)一词关系紧密;19世纪,“发展”成为社会科学古典进化论的关键词之一,特别用于解释经济变迁,尤其是工业化和市场经济的变迁过程;这一含义在20世纪日益普遍化,二战以后“发展”成为一种不言自明的概念,并且成为世界大多数人日常生活中的现实(Raym ond,1983Π1976:102-104)。这是西方发达资本主义国家的援助项目和新兴民族国家的发展欲望共同作用的结果。 自1949年美国总统杜鲁门提出“第四点计划”(以对落后国家提供经济援助的计划来支持和争取第三世界国家)以来,针对落后国家的直接经济援助项目成为推广西方现代资本主义发展模式的重要手段。20世纪的50、60年代,在古典经济学理论的基础上,这些发展项目集中体现了把经济增长作为社会发展目标的思想。这种发展模式在实践当中并未取得预期效果,反而引发了一系列复杂的社会经济问题,如文化冲 881