919 resultados para Project 2001-010-C : Investment Decision Framework for Infrastructure Assets Management
Resumo:
Työ tehtiin Steris Finn Aqualle, joka oli ottanut tuotantoon uuden autoklaavimallin kevään 2007 aikana. Työn tavoitteena oli kehittää painelaitteen hitsausta vertailemalla kevytmekanisointi, mekanisointi ja robotisointiratkaisuja ja hankkia riittävät tiedot mahdollisen investointipaatoksen tueksi. Tarkastellut kevytmekanisointilaitteet koostuivat kuljetinkiskosta, kuljettimesta ja mahdollisesta railonseurantalaitteesta. Tarkasteltu mekanisointijärjestelmä oli asiakaskohtaisesti räätälöitävä kokonaisuus. Tarkasteltuun hitsausrobottijärjestelmään kuului kappaleenkäsittelylaite sekä etäohjelmointiohjelmisto. Työn teoriaosassa käsiteltiin painelaitelainsäädännön vaikutuksia tuotantoon, ruostumattoman ja haponkestävän teräksen ominaisuuksia hitsauksen kannalta, tuotannossa käytettäviä hitsausprosesseja, hitsauksen mekanisointia ja automatisointia sekä railonseurantaa. Työn käytännön osuudessa käytiin läpi painelaitevalmistuksen nykytila. Painelaitevalmistus jaettiin eri työvaiheisiin ja työvaiheet analysoitiin, millä varmistettiin, että kehitysresurssit suunnataan oikeisiin kohteisiin. Kehitysehdotuksena esitettiin joko railonseurannalla varustetun kevytmekanisointilaitteiston tai etäohjelmoitavan hitsausrobottijärjestelmän hankintaa. Kevytmekanisoinnilla on mahdollista saavuttaa samat edut kuin kalliimmillakin mekanisointilaitteilla ja kevytmekanisoinnin etuna on käyttöönoton helppous ja laitteiston edullisuus. Hitsausrobotin hankintaan liittyy epävarmuustekijöitä, joiden tarkempi selvittäminen on tarpeen, ennen hitsausrobotin hankintapaatosta. Suuremmilla tuotantomäärillä hitsausrobottisolu olisi ollut selkeästi parempi ratkaisu.
Resumo:
Tässä diplomityössä on tutkittu epävarmuuden mallintamista investointilaskelmissa. Kirjallisuuden perusteella luotiin prosessimalli, jolla voidaan strukturoidusti tehdä yritysinvestointi- tai yritysirtaantumispäätös. Malli koostuu neljästä päävaiheesta, mutta pääpainopiste mallissa on laskentamenetelmissä. Luotua prosessimallia sekä erityisesti laskentamenetelmiä on sovellettu yritysesimerkin avulla. Epävarmuuden mallintamisongelmaa on käsitelty sekä perinteisten klassillisten investointiteorioiden että reaalioptioajatteluun pohjautuvien menetelmien avulla. Reaalioptioteoriaan perustuvien menetelmien avulla voidaan ottaa huomioon tulevat epävarmuudet ja päätöksentekomahdollisuudet. Perinteisten reaalioptioteorioiden käytännön elämän vastaisten taustaoletuksien vuoksi tutkittiin erityisesti uusimpia malleja. Diplomityössä yritysesimerkiksi valittiin Paroc Group, jonka yritysjärjestelytilannetta tutkittiin sen nykyisen omistajan eli pankin näkökulmasta. Diplomityön yhtenä keskeisenä tavoitteena oli selvittää, että kannattaako pankin myydä yhtiö tämän hetkisellä markkinahinnalla vai odottaa parempaa myyntiajankohtaa.
Resumo:
Investment decision-making on far-reaching innovation ideas is one of the key challenges practitioners and academics face in the field of innovation management. However, the management practices and theories strongly rely on evaluation systems that do not fit in well with this setting. These systems and practices normally cannot capture the value of future opportunities under high uncertainty because they ignore the firm’s potential for growth and flexibility. Real options theory and options-based methods have been offered as a solution to facilitate decision-making on highly uncertain investment objects. Much of the uncertainty inherent in these investment objects is attributable to unknown future events. In this setting, real options theory and methods have faced some challenges. First, the theory and its applications have largely been limited to market-priced real assets. Second, the options perspective has not proved as useful as anticipated because the tools it offers are perceived to be too complicated for managerial use. Third, there are challenges related to the type of uncertainty existing real options methods can handle: they are primarily limited to parametric uncertainty. Nevertheless, the theory is considered promising in the context of far-reaching and strategically important innovation ideas. The objective of this dissertation is to clarify the potential of options-based methodology in the identification of innovation opportunities. The constructive research approach gives new insights into the development potential of real options theory under non-parametric and closeto- radical uncertainty. The distinction between real options and strategic options is presented as an explanans for the discovered limitations of the theory. The findings offer managers a new means of assessing future innovation ideas based on the frameworks constructed during the course of the study.
Resumo:
How can the holy craft of liturgy be trained? A study of approaches to instruction in training oral skills within education of the Norwegian clergy The theme of this study is the competence of expression of clerics performing liturgies as part of their duties in the Norwegian Lutheran Church. The aim of the study is to find a teaching practice which can raise the competence in oral expression characteristic of the clergy profession. The teaching practice is explored and discussed within the context of the basic education of the clergy. The main thesis is formulated as a question: How can the holy craft of liturgy be trained? An underpinning of the study is that liturgical acts are holy, which gives these performances an aspect of otherness. This otherness constitutes a clear agreement between the students and the teacher, and between the professional and the employer. The pre-understanding of the researcher is that these liturgical oral acts are trainable, and that there is a need and a necessity to train in these skills. Three research questions are elaborated on in the explorative section of the study: • What is characteristic of a competence of expression connected to the profession? • How can this competence of expression connected to liturgical performance be developed? • What is the importance of this competence in the holy craft of liturgy for the development of a cohesive professional self-understanding? The study is based on a research and development project where the researcher as the teacher and students from one specific clergy education in Norway (MF) were the source of the empirical material. The empirical data came from practice with two external observers› logs on the coaching, video observations, of the teacher and the students› texts on the practice under study, which is liturgical performance. The researcher›s log and field notes also provide material for the analysis. This is a qualitative project and an arts education project carried out within an interpretative framework. The theoretical framework has three perspectives: a structural approach based on the system theory of Niklas Luhmann, an epistemological approach discussing forms of knowledge in practice or informing practice and an arts education approach. The results indicate that the competence in oral liturgical performance can be considered a trainable skill, and that this training can be understood as an arts education method of instruction based on meaningful communication, dramaturgical thinking and the development of authenticity. The main result from this study can be considered as articulating and sketching the contours of the field of knowledge where the students embody the meaning of the clergy profession ‒ and this articulation has an innovative potential as knowledge combining experience and theoretical understanding.
Resumo:
The most outstanding conceptual challenge of modern crisis management is the principle of consent. It is not a problem only at the operational level - it challenges the entire decision-making structures of crisis management operations. In post-cold war times and especially in the 21st century, there has been a transition from peacekeeping with limited size and scope towards large and complex peace operations. This shift has presented peace operations with a dilemma. How to balance between maintaining consent for peace operations, whilst being able to use military force to coerce those attempting to wreck peace processes? To address such a dilemma, this research aims to promote understanding, on what can be achieved by military crisis management operations (peace support operations) in the next decade. The research concentrates on the focal research question: Should military components induce consent or rely on the compliance of conflicting parties in crisis management operations of the next decade (2020 – 2030)? The focus is on military – political strategic level considerations, and especially on the time before political decisions to commit to a crisis management operation. This study does not focus on which actor or organisation should intervene. The framework of this thesis derives from the so called ‘peacebuilding space’, the scope of peace operations and spoiler theory. Feasibility of both peace enforcement and peacekeeping in countering future risk conditions are analysed in this framework. This future-orientated qualitative research uses the Delphi-method with a panel of national and international experts. Citation analysis supports identification of relevant reference material, which consists of contemporary literature, the Delphi-questionnaires and interviews. The research process followed three main stages. In the first stage, plausible future scenarios and risk conditions were identified with the Delphi-panel. In the second stage, operating environments for peace support operations were described and consequent hypotheses formulated. In the third stage, these hypotheses were tested on the Delphi-panel. The Delphi-panel is sufficiently wide and diverse to produce plausible yet different insights. The research design utilised specifically military crisis management and peace operations theories. This produced various and relevant normative considerations. Therefore, one may argue that this research; which is based on accepted contemporary theory, hypotheses derived thereof and utilising an expert panel, contributes to the realm of peace support operations. This research finds that some degree of peace enforcement will be feasible and necessary in at least the following risk conditions: failed governance; potential spillover of ethnic, religious, ideological conflict; vulnerability of strategic chokepoints and infrastructures in ungoverned spaces; as well as in territorial and extra-territorial border disputes. In addition, some form of peace enforcement is probably necessary in risk conditions pertaining to: extremism of marginalised groups; potential disputes over previously uninhabited and resource-rich territories; and interstate rivalry. Furthermore, this research finds that peacekeeping measures will be feasible and necessary in at least risk conditions pertaining to: potential spillover of ethnic, religious, ideological conflict; uncontrolled migration; consequences from environmental catastrophes or changes; territorial and extra-territorial border disputes; and potential disputes over previously uninhabited and resource-rich territories. These findings are all subject to both generic and case specific preconditions that must exist for a peace support operation. Some deductions could be derived from the research findings. Although some risk conditions may appear illogical, understanding the underlying logic of a conflict is fundamental to understanding transition in crisis management. Practitioners of crisis management should possess cognizance of such transition. They must understand how transition should occur from threat to safety, from conflict to stability – and so forth. Understanding transition is imperative for managing the dynamic evolution of preconditions, which begins at the outset of a peace support operation. Furthermore, it is pertinent that spoilers are defined from a peace process point of view. If spoilers are defined otherwise, it changes the nature of an operation towards war, where the logic is breaking the will of an enemy - and surrender. In peace support operations, the logic is different: actions towards spoilers are intended to cause transition towards consent - not defeat. Notwithstanding future developments, history continues to provide strategic education. However, the distinction is that the risk conditions occur in novel futures. Hence, lessons learned from the past should be fitted to the case at hand. This research shows compelling evidence that swaying between intervention optimism and pessimism is not substantiated. Both peace enforcement and peacekeeping are sine qua non for successful military crisis management in the next decade.
Resumo:
The objective of this study and paper was to find out how the strategic change management readiness in organizations can be evaluated. Based on theory and prior CMP model, the framework of strategic change management and issues related to it was constructed. Additionally a synthesis of the most important phases and interventions in strategic change process and project was created. These phases were starting point, planning, implementation and evaluation and securing phases. Qualitative approach was utilized in the empirical part of the study due to the need for in-depth information about the topics surveyed through semi-structured interview. There were 18 responders from the top management of large Finnish companies. In this study interventions, strengths and weaknesses during the various phases of strategic change projects were revealed. Additionally the interviewees’ opinion on the importance of each of the interventions in strategic change project success was asked. According to this study, the most important phases recognized through researching theoretical literature, prior CMP model and empirical information in starting point phase were analysis of current and desired state and need for change accompanied with guiding coalition formulation. In planning phase the most important interventions were project organization formulation, action plan creation, analysis of prior and current strategic change projects and organizational structure analysis. In the change project implementation phase the interventions of importance were launch, quick wins, sense of urgency creation, change resistance management and change communications. In the final evaluation and securing phase project evaluation was the most important intervention. Based on the results a tool for creating change management readiness profile was created.
Resumo:
Combating climate change is one of the key tasks of humanity in the 21st century. One of the leading causes is carbon dioxide emissions due to usage of fossil fuels. Renewable energy sources should be used instead of relying on oil, gas, and coal. In Finland a significant amount of energy is produced using wood. The usage of wood chips is expected to increase in the future significantly, over 60 %. The aim of this research is to improve understanding over the costs of wood chip supply chains. This is conducted by utilizing simulation as the main research method. The simulation model utilizes both agent-based modelling and discrete event simulation to imitate the wood chip supply chain. This thesis concentrates on the usage of simulation based decision support systems in strategic decision-making. The simulation model is part of a decision support system, which connects the simulation model to databases but also provides a graphical user interface for the decisionmaker. The main analysis conducted with the decision support system concentrates on comparing a traditional supply chain to a supply chain utilizing specialized containers. According to the analysis, the container supply chain is able to have smaller costs than the traditional supply chain. Also, a container supply chain can be more easily scaled up due to faster emptying operations. Initially the container operations would only supply part of the fuel needs of a power plant and it would complement the current supply chain. The model can be expanded to include intermodal supply chains as due to increased demand in the future there is not enough wood chips located close to current and future power plants.
Resumo:
My dissertation is an interdisciplinary study of the relationship between the Swiss peasants and nobles in Friedrich Schiller’s play Wilhelm Tell (1804). Changes to this relationship are of particular interest. Communication in the play is examined via a micro-analysis based on Penelope Brown’s and Stephen C. Levinson’s theoretical framework Politeness: Some universals in language usage. (1978, 1987). Brown and Levinson distinguish between positivepoliteness and negative-politeness strategies and their distinction is useful for my argument, since they claim that the use of positive-politeness strategies reflects the speaker’s intention to minimize the distance between the interlocutors (Brown and Levinson 1987: 103). Negative-politeness strategies, by contrast, result in social distancing (Brown and Levinson 1987: 130). In accordance with Brown’s and Levinson’s theory, it can be argued that the distribution of positive-politeness and negative-politeness strategies reflects changes in the distance between the fictional interlocutors as representatives of their social classes in Wilhelm Tell. The analysis of the communication in the play highlights that existing conflicts within the social groups are resolved and replaced with solidarity (cf. ‘Claim ’common ground’ and ‘Claim in-group membership with H’) before the peasants and noblemen appear on stage simultaneously in III, 3. In the scene in question, Geßler forces Tell to shoot the apple off his son’s head. Although both nobles and peasants are present, they do not communicate with each other. Thus, communication between the social classes occurs for the first time in IV, 2. This scene is crucial with regard to the changes in the relationship between the social classes in the play. The younger generation, with Rudenz as a representative of the nobility and Melchthal as a representative of the peasants, break with the prevailing conventions and initiate a new type of cooperation based on mutual helping and equality in the right and the duty to protect the country from the violent oppressors representing Habsburg (cf. ‘Convey that S and H are cooperators’, ‘Claim reflexivity’ and ‘Claim reciprocity’). The linguistic analysis reveals the crucial role of the Swiss nobility in the development of the social utopia, as well as the non-contribution of Wilhelm Tell. In fact, Tell never communicates with the Swiss noblemen. The role of the nobility and the role of Wilhelm Tell are further investigated in a comparison between Schiller’s Wilhelm Tell and four of Schiller’s historical sources. These sources, which contain earlier, non-dramatic versions of the establishment of the Swiss Confederation, are the following: Kronica von der loblichen Eydtgnoschaft compiled by Petermann Etterlin (1507), Gemeiner loblicher Eydgnoschafft Stetten Landen vnd Völckeren Chronik wirdiger thaaten beschreybung (1548) written by Johann Stumpf, Chronicon Helveticum of Aegidius Tschudi (the publication of Iselin from 1734 and 1736) and Johannes von Müller’s Geschichten schweizerischer Eidgenossenschaft (1786). Thecomparison sheds light on the fact that both Tschudi and von Müller emphasize unity among the Swiss and cooperation in their attempt to defeat the enemy. However, Schiller has reinforced the role of the nobility in the cooperation. In addition, the comparison between Schiller’s play and the historical sources reveals profound differences with regard to the role of Wilhelm Tell. In all of Schiller’s sources, Tell is present at Rütli, whereas he is absent from Rütli in Schiller’s play. In the play in general, Tell is conspicuously separated from the other peasants. Explanations of my linguistic results, which correspond to the above mentioned differences between the roles of the figures in Wilhelm Tell and the depictions in Schiller’s sources, are found by comparing the path of Schiller’s Swiss towards an egalitarian perspective with the kind of social evolution depicted by the German philosopher Johann Benjamin Erhard in his essay Über das Recht des Volks zu einer Revolution (1795). Aiming at considering Schiller’s social utopia within the larger cultural framework of the German response to the French Revolution, the comparison suggests that both authors depict the need for social change in terms of a change in social hierarchies (Erhard 1970: 95-96, cf. Foi 2005: 225). Erhard’s essay thus helps explain the political intention of Schiller’s play to keep the ideals of the French Revolution as crucial aims but profoundly change the means towards freedom and equality. In his attempt to claim the political resistance of the nobles and peasants as just, however, Schiller sacrificed the figure of Wilhelm Tell. Guilty of the murder of Geßler, Tell was no longer suitable for the righteous revolution imagined by Schiller (cf. Bloch 2008: 215 and Schulz 2005: 228). This explains Tell’s absence in the Rütli scene, his isolation in the plot, as well as his non-contribution to the social utopia. Together, the linguistic analysis and contextualisation of Schiller’s play support my hypothesis that Wilhelm Tell describes a process of change in the relationship between peasants and nobles. The interdisciplinary approach to the topic proved to be fruitful for all areas of the research involved.
Resumo:
Centrifugal pumps are one of the major energy consuming end-devices in developed coun-tries both in industrial and services sectors. According to recent studies, even 30 % of the energy used in pumping systems could be saved by more careful choosing of devices and system design. One of the most efficient and affordable ways to decrease the energy con-sumption of the pumping system is to substitute traditionally used flow control methods, like valve control, with modern variable speed drive (VSD) control. In this thesis, Microsoft Excel based program, Savings Calculator for Centrifugal Pumps (SCCP), is designed. SCCP calculates the achievable energy and financial savings when throttle control is substituted by VSD control in the pumping system. Compared to the sim-ilar existing programs, the goal is to make SCCP calculations more accurate and require less input information. Also some useful additional features are added to the designed program to make it more user friendly. The reliability of the calculations of designed program seem to vary depending on case. The results are corresponding accurately to the laboratory measurements, but there occurs high deviations in some cases, when the results are compared to the pump information specified by manufacturer. On the basis of verification in this thesis, SCCP seems to be at least as accurate as similar existing programs and it can be used as help in investment decision whether to have VSD or not.
Resumo:
Linguistic modelling is a rather new branch of mathematics that is still undergoing rapid development. It is closely related to fuzzy set theory and fuzzy logic, but knowledge and experience from other fields of mathematics, as well as other fields of science including linguistics and behavioral sciences, is also necessary to build appropriate mathematical models. This topic has received considerable attention as it provides tools for mathematical representation of the most common means of human communication - natural language. Adding a natural language level to mathematical models can provide an interface between the mathematical representation of the modelled system and the user of the model - one that is sufficiently easy to use and understand, but yet conveys all the information necessary to avoid misinterpretations. It is, however, not a trivial task and the link between the linguistic and computational level of such models has to be established and maintained properly during the whole modelling process. In this thesis, we focus on the relationship between the linguistic and the mathematical level of decision support models. We discuss several important issues concerning the mathematical representation of meaning of linguistic expressions, their transformation into the language of mathematics and the retranslation of mathematical outputs back into natural language. In the first part of the thesis, our view of the linguistic modelling for decision support is presented and the main guidelines for building linguistic models for real-life decision support that are the basis of our modeling methodology are outlined. From the theoretical point of view, the issues of representation of meaning of linguistic terms, computations with these representations and the retranslation process back into the linguistic level (linguistic approximation) are studied in this part of the thesis. We focus on the reasonability of operations with the meanings of linguistic terms, the correspondence of the linguistic and mathematical level of the models and on proper presentation of appropriate outputs. We also discuss several issues concerning the ethical aspects of decision support - particularly the loss of meaning due to the transformation of mathematical outputs into natural language and the issue or responsibility for the final decisions. In the second part several case studies of real-life problems are presented. These provide background and necessary context and motivation for the mathematical results and models presented in this part. A linguistic decision support model for disaster management is presented here – formulated as a fuzzy linear programming problem and a heuristic solution to it is proposed. Uncertainty of outputs, expert knowledge concerning disaster response practice and the necessity of obtaining outputs that are easy to interpret (and available in very short time) are reflected in the design of the model. Saaty’s analytic hierarchy process (AHP) is considered in two case studies - first in the context of the evaluation of works of art, where a weak consistency condition is introduced and an adaptation of AHP for large matrices of preference intensities is presented. The second AHP case-study deals with the fuzzified version of AHP and its use for evaluation purposes – particularly the integration of peer-review into the evaluation of R&D outputs is considered. In the context of HR management, we present a fuzzy rule based evaluation model (academic faculty evaluation is considered) constructed to provide outputs that do not require linguistic approximation and are easily transformed into graphical information. This is achieved by designing a specific form of fuzzy inference. Finally the last case study is from the area of humanities - psychological diagnostics is considered and a linguistic fuzzy model for the interpretation of outputs of multidimensional questionnaires is suggested. The issue of the quality of data in mathematical classification models is also studied here. A modification of the receiver operating characteristics (ROC) method is presented to reflect variable quality of data instances in the validation set during classifier performance assessment. Twelve publications on which the author participated are appended as a third part of this thesis. These summarize the mathematical results and provide a closer insight into the issues of the practicalapplications that are considered in the second part of the thesis.
Resumo:
The main objective of the study was to form a strategic process model and project management tool to help IFRS change implementation projects in the future. These research results were designed based on the theoretical framework of Total Quality Management and leaning on the facts that were collected during the empirical case study of IAS 17 change. The us-age of the process oriented approach in IFRS standard change implementation after the initial IFRS implementation is rationalized with the following arguments: 1) well designed process tools lead to optimization of resources 2) With the help of process stages and related tasks it is easy to ensure the efficient way of working and managing the project as well as make sure to include all necessary stakeholders to the change process. This research is following the qualitative approach and the analysis is in describing format. The first part of the study is a literature review and the latter part has been conducted as a case study. The data has been col-lected in the case company with interviews and observation. The main findings are a process model for IFRS standard change process and a check-list formatted management tool for up-coming IFRS standard change projects. The process flow follows the main cornerstones in IASB’s standard setting process and the management tool has been divided to stages accordingly.
Resumo:
In the new age of information technology, big data has grown to be the prominent phenomena. As information technology evolves, organizations have begun to adopt big data and apply it as a tool throughout their decision-making processes. Research on big data has grown in the past years however mainly from a technical stance and there is a void in business related cases. This thesis fills the gap in the research by addressing big data challenges and failure cases. The Technology-Organization-Environment framework was applied to carry out a literature review on trends in Business Intelligence and Knowledge management information system failures. A review of extant literature was carried out using a collection of leading information system journals. Academic papers and articles on big data, Business Intelligence, Decision Support Systems, and Knowledge Management systems were studied from both failure and success aspects in order to build a model for big data failure. I continue and delineate the contribution of the Information System failure literature as it is the principal dynamics behind technology-organization-environment framework. The gathered literature was then categorised and a failure model was developed from the identified critical failure points. The failure constructs were further categorized, defined, and tabulated into a contextual diagram. The developed model and table were designed to act as comprehensive starting point and as general guidance for academics, CIOs or other system stakeholders to facilitate decision-making in big data adoption process by measuring the effect of technological, organizational, and environmental variables with perceived benefits, dissatisfaction and discontinued use.
Resumo:
This paper aims at reconciling the evidence that sophisticated valuation models are increasingly used by companies in their investment appraisal with the literature of bounded rationality, according to which objective optimization is impracticable in the real world because it would demand an immense level of sophistication of the analytical and computational processes of human beings. We show how normative valuation models should rather be viewed as forms of reality representation, frameworks according to which the real world is perceived, fragmented for a better understanding, and recomposed, providing an orderly method for undertaking a task as complex as the investment decision.
Resumo:
In the new age of information technology, big data has grown to be the prominent phenomena. As information technology evolves, organizations have begun to adopt big data and apply it as a tool throughout their decision-making processes. Research on big data has grown in the past years however mainly from a technical stance and there is a void in business related cases. This thesis fills the gap in the research by addressing big data challenges and failure cases. The Technology-Organization-Environment framework was applied to carry out a literature review on trends in Business Intelligence and Knowledge management information system failures. A review of extant literature was carried out using a collection of leading information system journals. Academic papers and articles on big data, Business Intelligence, Decision Support Systems, and Knowledge Management systems were studied from both failure and success aspects in order to build a model for big data failure. I continue and delineate the contribution of the Information System failure literature as it is the principal dynamics behind technology-organization-environment framework. The gathered literature was then categorised and a failure model was developed from the identified critical failure points. The failure constructs were further categorized, defined, and tabulated into a contextual diagram. The developed model and table were designed to act as comprehensive starting point and as general guidance for academics, CIOs or other system stakeholders to facilitate decision-making in big data adoption process by measuring the effect of technological, organizational, and environmental variables with perceived benefits, dissatisfaction and discontinued use.
Resumo:
Keynes and the concept of capital: some epistemological observations in regard to the Sraffian premises of the General Theory. This article aims to examine the conception of the nature of capital used by Keynes in the General Theory, to show to what extent this concept is similar to Sraffa's conception, and to highlight the implications related to this concept, in terms of structural instability. So I will study the mechanisms that explain the investment decision in an environment with strong uncertainty, the modalities of aggregation of different generations of capital and the instability of equilibrium. The convergence between the keynesian and the Sraffian approaches comes from this common conception of capital. Finally, i will examine the implications in regard to the structure of the aggregate models.