101 |
Managing Wind-based Electricity Generation and StorageZhou, Yangfang 01 November 2012 (has links)
Among the many issues that profoundly affect the world economy every day, energy is one of the most prominent. Countries such as the U.S. strive to reduce reliance on the import of fossil fuels, and to meet increasing electricity demand without harming the environment.
Two of the most promising solutions for the energy issue are to rely on renewable energy, and to develop efficient electricity storage. Renewable energy—such as wind energy and solar energy—is free, abundant, and most importantly, does not exacerbate the global warming problem. However, most renewable energy is inherently intermittent and variable, and thus can benefit greatly from coupling with electricity storage, such as grid-level industrial batteries. Grid storage can also help match the supply and demand of an entire electricity market. In addition, electricity storage such as car batteries can help reduce dependence on oil, as it can enable the development of Plug-in Hybrid Electric Vehicles, and Battery Electric Vehicles. This thesis focuses on understanding how to manage renewable energy and electricity storage properly together, and electricity storage alone.
In Chapter 2, I study how to manage renewable energy, specifically wind energy. Managing wind energy is conceptually straightforward: generate and sell as much electricity as possible when prices are positive, and do nothing otherwise. However, this leads to curtailment when wind energy exceeds the transmission capacity, and possible revenue dilution when current prices are low but are expected to increase in the future. Electricity storage is being considered as a means to alleviate these problems, and also enables buying electricity from the market for later resale. But the presence of storage complicates the management of electricity generation from wind, and the value of storage for a wind-based generator is not entirely understood.
I demonstrate that for such a combined generation and storage system the optimal policy does not have any apparent structure, and that using overly simple policies can be considerably suboptimal. I thus develop and analyze a triple-threshold policy that I show to be nearoptimal. Using a financial engineering price model and calibrating it to data from the New York Independent System Operator, I show that storage can substantially increase the monetary value of a wind farm: If transmission capacity is tight, the majority of this value arises from reducing curtailment and time-shifting generation; if transmission capacity is abundant this value stems primarily from time-shifting generation and arbitrage. In addition, I find that while more storage capacity always increases the average energy sold to the market, it may actually decrease the average wind energy sold when transmission capacity is abundant.
In Chapter 3, I examine how electricity storage can be used to help match electricity supply and demand. Conventional wisdom suggests that when supply exceeds demand, any electricity surpluses should be stored for future resale. However, because electricity prices can be negative, another potential strategy of dealing with surpluses is to destroy them. Using real data, I find that for a merchant who trades electricity in a market, the strategy of destroying surpluses is potentially more valuable than the conventional strategy of storing surpluses.
In Chapter 4, I study how the operation and valuation of electricity storage facilities can be affected by their physical characteristics and operating dynamics. Examples are the degradation of energy capacity over time and the variation of round-trip efficiency at different charging/discharging rates. These dynamics are often ignored in the literature, thus it has not been established whether it is important to model these characteristics. Specifically, it remains an open question whether modeling these dynamics might materially change the prescribed operating policy and the resulting valuation of a storage facility. I answer this question using a representative setting, in which a battery is utilized to trade electricity in an energy arbitrage market.
Using engineering models, I capture energy capacity degradation and efficiency variation explicitly, evaluating three types of batteries: lead acid, lithium-ion, and Aqueous Hybrid Ion— a new commercial battery technology. I calibrate the model for each battery to manufacturers’ data and value these batteries using the same calibrated financial engineering price model as in Chapter 2. My analysis shows that: (a) it is quite suboptimal to operate each battery as if it did not degrade, particularly for lead acid and lithium-ion; (b) reducing degradation and efficiency variation have a complimentary effect: the value of reducing both together is greater than the sum of the value of reducing one individually; and (c) decreasing degradation may have a bigger effect than decreasing efficiency variation.
|
102 |
Cognitive Style Diversity in TeamsAggarwal, Ishani 01 January 2013 (has links)
In this dissertation, I undertake the study of cognitive styles in teams in three papers. Cognitive styles are psychological dimensions that represent consistencies in how individuals acquire and process information, and guide their performance on information processing, decision making, problem solving, and creativity tasks. In addition, they distinguish between individuals from different educational and functional areas. They constitute an important, though largely underrepresented, area of team research. I investigate the relationship between cognitive style diversity and team performance on tasks that impose different demands on teams- execution and creativity. Across the three papers, I identify important processes such as strategic focus, strategic consensus, transactive memory, and learning that further explicate this relationship. The studies move the ongoing debate about whether and how diversity is beneficial and detrimental to team performance forward by exploring task contexts that benefit from diversity, and those that do not. In the final paper, I highlight one effective way to optimize the opposing forces that make diversity a challenging phenomenon to study, thus attempting to move the debate toward a resolution.
In the first paper, I investigate the effect of members’ cognitive styles on team processes that affect errors in execution tasks. In two laboratory studies, I investigate how a team’s composition (members’ cognitive styles related to object and spatial visualization) affects the team’s strategic focus and strategic consensus, and how those affect the team’s commission of errors. Errors have crucial implications for many real-life organizational teams carrying out execution tasks. Study 1, conducted with 70 dyads performing a navigation and identification task, established that teams high in spatial visualization are more process-focused than teams high in object visualization. Process focus, which pertains to a team’s attention to the details of conducting a task, is associated with fewer errors. Study 2, conducted with 64 teams performing a building task, established that heterogeneity in cognitive style is negatively associated with the formation of a strategic consensus, which has a direct and mediating relationship with errors.
In the second paper, I investigate the effect of team members’ cognitive style composition, and related team processes, on creativity. Creativity encompasses the processes leading to the generation of novel and useful ideas. In a study with 112 graduate-student teams working on a semester-long project, I explore the effect of the team’s cognitive style composition on its transactive memory and strategic consensus, and find that it influences both these processes. Furthermore, I find that team’s transactive memory is positively related to two aspects of creativity: flexibility and fluency. Originality, the third aspect of creativity is influenced by the team’s strategic consensus and strategic focus. The study provides a nuanced understanding of how diverse inputs, but integrating processes, benefit team creativity.
In the third paper I highlight that cognitive diversity in teams is associated with both benefits and costs, and increasing the benefits linked with having a greater wealth of human resources without increasing the associated coordination costs is a challenge. In this paper, I provide a new lens for looking at team composition in terms of this cost-benefit tradeoff, and propose one way to optimize it. I study how cognitive resources are distributed in teams, emphasizing both breadth and depth, and investigate the influence of versatile team members, or members who encompass depth in a breadth of domains. In two studies, I find evidence for the proposition that the number of cognitively versatile members in the team is positively associated with team performance in execution tasks, explaining variance above and beyond standard and non-standard ways of capturing diversity. Interestingly, I find that while there is generally a curvilinear (inverted U-shaped) relationship between team size and team performance, there is a positive linear relationship between size and performance in teams that have cognitively versatile members. I also find that the positive impact of cognitively versatile members on performance in execution tasks is facilitated by process learning. I discuss the implications of this alternative way of viewing diversity.
Taken together, this dissertation explores team composition using deep-level diversity variables that directly relate to functional areas of individuals in organizations. The three papers contribute to an underrepresented area of organizational research, and establish the importance of the team’s cognitive style composition to team performance. Also, by addressing many calls in the groups and teams research literature, this dissertation aims at providing a nuanced understanding of composition, processes and performance in teams, revealing the complexity of teamwork.
|
103 |
Understanding the Strength of General-Purpose Cutting PlanesMolinaro, Marco 01 January 2013 (has links)
Cutting planes for a mixed-integer program are linear inequalities which are satisfied by all feasible solutions of the latter. These are fundamental objects in mixed-integer programming that are critical for solving large-scale problems in practice. One of the main challenge in employing them is that there are limitless possibilities for generating cutting planes; the selection of the strongest ones is crucial for their effective use. In this thesis, we provide a principled study of the strength of generalpurpose cutting planes, giving a better understanding of the relationship between the different families of cuts available and analyzing the properties and limitations of our current methods for deriving cuts.
We start by analyzing the strength of disjunctive cuts that generalize the ubiquitous split cuts. We first provide a complete picture of the containment relationship of the split closure, second split closure, cross closure, crooked cross closure and tbranch split closure. In particular, we show that rank-2 split cuts and crooked cross cuts are neither implied by cross cuts, which points out the limitations of the latter; these results answer questions left open in [56, 65]. Moreover, given the prominent role of relaxations and their computational advantages, we explore how strong are cross cuts obtained from basic and 2-row relaxations. Unfortunately we show that not all cross cuts can be obtained as cuts based on these relaxation, answering a question left open in [56]. One positive message from this result, though, is that cross cuts do not suffer from the limitations of these relaxations.
Our second contribution is the introduction of a probabilistic model for comparing the strength of families of cuts for the continuous relaxation. We employ this model to compare the important split and triangle cuts, obtaining results that provide improved information about their behavior. More precisely, while previous works indicated that triangle cuts should be much stronger than split cuts, we provide the first theoretical support for the effect that is observed in practice: for most instances, these cuts have the same strength.
In our third contribution, we study the multi-dimensional infinite relaxation introduced by Gomory and Johnson in the late 60’s, which has been an important tool for analyzing and obtaining insights on cutting planes. The celebrated Gomory- Johnson’s 2-Slope Theorem gives a sufficient condition for a cut to be facet defining from the 1-row infinite relaxation. We provide an extension of this result for the k-row case, for arbitrary k, which we call the (k + 1)-Slope Theorem. Despite increasing interest in understanding the multi-row case, no such extension was known prior to our work. This result, together with the relevance of 2-slope functions for the 1-dimensional case, indicates that (k + 1)-slope functions might lead to strong cuts in practice.
In our fourth contribution, we consider cuts that generalize Gomory fractional cuts but take into account upper bounds imposed on the variables. More specifically, we revisit the lopsided cuts obtained recently by Balas and Qualizza via a disjunctive procedure. We give a geometric interpretation of these cuts, viewing them as cuts for the infinite relaxation that are strengthened by a geometric lifting procedure. Using this perspective, we are able to generalize these cuts to obtain a family of cuts which has on one end the GMI cut, and on the other end the lopsided cuts. We show that all these cuts are “new”, namely they are all facets of the infinite relaxation with upper bounded basic variable. We conclude by presenting preliminary experimental results, which unfortunately shows that these cuts decrease in importance as they move away from the GMI inequality, complementing the experimental results from Balas and Qualizza.
In our final contribution, we further explore properties and characterizations of split cuts, focusing on a general model of mixed-integer corner relaxation. The backbone of this work is a description of the split cuts for this relaxation from the perspective of cut-generating functions; this essentially establishes the equivalence of split cuts and (a generalization of) the k-cuts [50]. As our previous result, this characterization is obtained using the geometric lifting idea, illustrating its flexibility as a tool for analyzing cuts. As a consequence, we show that every split cut for a corner relaxation is the restriction of a split cut for the mixed-integer infinite relaxation, which further indicates the universality of the latter. As another consequence, we construct a pure-integer set with arbitrarily weak split closure, giving a pure-integer counterpart of the mixed-integer construction from [27].
|
104 |
A Computer Simulation Model of Municipal Resource AllocationCrecine, John P. 01 May 1966 (has links)
This report contains a description of a particular kind of governmental decision making “ the decisional behavior connected with municipal operating budgets. The theory is stated in the language of a computer program. The model of governmental problem solving is applied to the cities of Cleveland, Detroit, and Pittsburgh. The Model, with appropriate parameter estimates, is used to reproduce operating budget decisions in the three cities* In addition various naive models are tested and then compared with our decision Model (Section 6). Analysis of model residuals (Section 7) and a sensitivity analysis of some model parameters (Section 10) • is used to study "unprogrammed" aspects of budgetary behavior. The formal Model (presented in Section 4) is also related to various theories of individual and organizational behavior in Section 9. The behavioral antecedents of the model are discussed in Section 5* Implications o r the study for political research are touched on in Section 11 and our positive model forms the basis for a normative discussion of municipal resource allocation in Section 12.
|
105 |
Developing and testing a model of cooperative interorganisational relationships (IORs) in product innovation in an Australian manufacturing context: a multi-stakeholder perspectivevon der Heidt, Tania Unknown Date (has links)
As fast-growth economies, such as China and India are dominating export markets, innovation in the manufacturing industries of slower, developed economies, such as Australia is a survival issue. Particularly small- and medium-sized manufacturing enterprises (SMMEs) with limited internal innovation resources and capabilities are suffering. Corresponding with this development, academic interest in analysing the relationship between innovative performance of small firms and their recourse to external resources, especially through interorganisational relationships (IORs) has been growing over the last ten to fifteen years. To date the emerging literature has given limited attention to the systematic empirical assessment of the relationship and innovation inputs and outputs of cooperative product innovation. Furthermore, most of the literature focuses on cooperative innovation IORs with customer stakeholders, ignoring the potential role played by other external stakeholder groups, such as suppliers, industry partners and research/advisory organisations. To this end, this thesis investigated the following research question: What are the relationships between IOR- and innovation-oriented antecedents and consequences of cooperative product innovation and how effective for overall firm performance is product innovation cooperation with multiple stakeholders? A six-factor multi-stakeholder model of cooperative IORs in product innovation for Australian manufacturers was developed from a strategy-structure-performance-based model of marketing channel relationship structure. It synthesised and built upon prior models of cooperative product innovation and incorporated concepts and measures drawn from the IOR and product innovation literatures. The central, structure-based construct (measurement model) developed was stakeholder involvement in product innovation (SIPI). Two factors were used to predict SIPI: Stakeholder orientation (SO) and Product innovation orientation (PIO). A further two factors represented outcomes of SIPI: Relationship quality (RQ) and Product innovation performance (PIP). A sixth factor - Overall firm performance (OFP) - was also measured to assess the broader implications of the model. Two objective, single-item variables were also included in the model – relative Product innovation spending (associated with PIO) and Sales growth (associated with OFP).To address the multi-stakeholder perspective, four external stakeholder groups most likely to be involved in a manufacturer’s product innovation (customers, suppliers, industry partners (competitors) and research/advisory organisations) were assessed. Eight hypotheses positing associations between the six constructs were developed. As strategic data was required, the research method for primary data collection was a survey of CEOs/General Managers of Australian machinery and equipment manufacturers, predominately SMMEs. A questionnaire was designed to measure their opinions about the firm’s relationships with each of the four stakeholder groups in product innovation as well as their views on the firm’s product innovation orientation and performance. Following extensive pre-testing of the questionnaire, it was distributed by mail and online to the senior managers. Data obtained from 120 respondents was used in the research.Using a two-step structural equation modelling (SEM): confirmatory factor analysis (CFA) approach, examinations of parameter estimates, fit and residuals were used to test the individual constructs for validity. Composite reliability and average variance extracted were used to test for construct reliability. An overall (multi-stakeholder) structural model, as well as four single-stakeholder models, of key relationship- and innovation-oriented antecedents and consequences of cooperative product innovation were then tested using SEM AMOS software. Meaningful modifications of the hypothesised model were undertaken to improve model fit. The four modified single-stakeholder models and the overall (multistakeholder) model were found to provide a satisfactory fit. Statistically significant standard coefficients for each of the latent constructs provided evidence of the importance of each element as an input or outcome of cooperative innovation. The results indicated that, as posited, a firm’s Product innovation orientation (PIO) was positively associated with its Stakeholder orientation (SO). SO, in turn, was a valid antecedent of cooperative product innovation (SIPI). The hypothesised direct path from SIPI to RQ was, however, not supported. Instead, SIPI was found to partially mediate the SO-RQ association, further strengthening that positive link. Surprisingly, PIO did not appear to significantly influence cooperative innovation SIPI. Instead, PIO was found to be a strong and direct antecedent of market- and technical-oriented PIP, whereby the cooperative innovation construct SIPI did not materially impact Product innovation performance PIP. Product innovation spending directly influenced technical-oriented PIP only. RQ was a valid predictor of Sales growth, but not of Overall firm performance OFP. While market-oriented PIP was found to lead to stronger assessments of OFP, increased technical-oriented PIP negatively impacted on OFP. Consequently, seven of the eight hypotheses relating to the research model were accepted in part or full, and one hypothesis was rejected.Overall, qualified support was found for the central proposition: Higher (sales) growth manufacturers tend to pay more attention to their relationships with the top firms in each of four stakeholders groups (customers, suppliers, industry partners and advisory/research firms), involve these firms more in product innovation activities and perceive their relationships to be of higher ‘quality’. Firms with sound overall firm performance (return on investment, net profit, market share and overall business performance) tend to be more product innovation focused (in terms of strategy and spending) and achieve product innovations, which are successful both technologically and market-wise. However, stakeholder involvement in product innovation is not as good a predictor of product innovation outcomes as is the firm’s product innovation orientation (strategy).
|
106 |
Developing and testing a model of cooperative interorganisational relationships (IORs) in product innovation in an Australian manufacturing context: a multi-stakeholder perspectivevon der Heidt, Tania Unknown Date (has links)
As fast-growth economies, such as China and India are dominating export markets, innovation in the manufacturing industries of slower, developed economies, such as Australia is a survival issue. Particularly small- and medium-sized manufacturing enterprises (SMMEs) with limited internal innovation resources and capabilities are suffering. Corresponding with this development, academic interest in analysing the relationship between innovative performance of small firms and their recourse to external resources, especially through interorganisational relationships (IORs) has been growing over the last ten to fifteen years. To date the emerging literature has given limited attention to the systematic empirical assessment of the relationship and innovation inputs and outputs of cooperative product innovation. Furthermore, most of the literature focuses on cooperative innovation IORs with customer stakeholders, ignoring the potential role played by other external stakeholder groups, such as suppliers, industry partners and research/advisory organisations. To this end, this thesis investigated the following research question: What are the relationships between IOR- and innovation-oriented antecedents and consequences of cooperative product innovation and how effective for overall firm performance is product innovation cooperation with multiple stakeholders? A six-factor multi-stakeholder model of cooperative IORs in product innovation for Australian manufacturers was developed from a strategy-structure-performance-based model of marketing channel relationship structure. It synthesised and built upon prior models of cooperative product innovation and incorporated concepts and measures drawn from the IOR and product innovation literatures. The central, structure-based construct (measurement model) developed was stakeholder involvement in product innovation (SIPI). Two factors were used to predict SIPI: Stakeholder orientation (SO) and Product innovation orientation (PIO). A further two factors represented outcomes of SIPI: Relationship quality (RQ) and Product innovation performance (PIP). A sixth factor - Overall firm performance (OFP) - was also measured to assess the broader implications of the model. Two objective, single-item variables were also included in the model – relative Product innovation spending (associated with PIO) and Sales growth (associated with OFP).To address the multi-stakeholder perspective, four external stakeholder groups most likely to be involved in a manufacturer’s product innovation (customers, suppliers, industry partners (competitors) and research/advisory organisations) were assessed. Eight hypotheses positing associations between the six constructs were developed. As strategic data was required, the research method for primary data collection was a survey of CEOs/General Managers of Australian machinery and equipment manufacturers, predominately SMMEs. A questionnaire was designed to measure their opinions about the firm’s relationships with each of the four stakeholder groups in product innovation as well as their views on the firm’s product innovation orientation and performance. Following extensive pre-testing of the questionnaire, it was distributed by mail and online to the senior managers. Data obtained from 120 respondents was used in the research.Using a two-step structural equation modelling (SEM): confirmatory factor analysis (CFA) approach, examinations of parameter estimates, fit and residuals were used to test the individual constructs for validity. Composite reliability and average variance extracted were used to test for construct reliability. An overall (multi-stakeholder) structural model, as well as four single-stakeholder models, of key relationship- and innovation-oriented antecedents and consequences of cooperative product innovation were then tested using SEM AMOS software. Meaningful modifications of the hypothesised model were undertaken to improve model fit. The four modified single-stakeholder models and the overall (multistakeholder) model were found to provide a satisfactory fit. Statistically significant standard coefficients for each of the latent constructs provided evidence of the importance of each element as an input or outcome of cooperative innovation. The results indicated that, as posited, a firm’s Product innovation orientation (PIO) was positively associated with its Stakeholder orientation (SO). SO, in turn, was a valid antecedent of cooperative product innovation (SIPI). The hypothesised direct path from SIPI to RQ was, however, not supported. Instead, SIPI was found to partially mediate the SO-RQ association, further strengthening that positive link. Surprisingly, PIO did not appear to significantly influence cooperative innovation SIPI. Instead, PIO was found to be a strong and direct antecedent of market- and technical-oriented PIP, whereby the cooperative innovation construct SIPI did not materially impact Product innovation performance PIP. Product innovation spending directly influenced technical-oriented PIP only. RQ was a valid predictor of Sales growth, but not of Overall firm performance OFP. While market-oriented PIP was found to lead to stronger assessments of OFP, increased technical-oriented PIP negatively impacted on OFP. Consequently, seven of the eight hypotheses relating to the research model were accepted in part or full, and one hypothesis was rejected.Overall, qualified support was found for the central proposition: Higher (sales) growth manufacturers tend to pay more attention to their relationships with the top firms in each of four stakeholders groups (customers, suppliers, industry partners and advisory/research firms), involve these firms more in product innovation activities and perceive their relationships to be of higher ‘quality’. Firms with sound overall firm performance (return on investment, net profit, market share and overall business performance) tend to be more product innovation focused (in terms of strategy and spending) and achieve product innovations, which are successful both technologically and market-wise. However, stakeholder involvement in product innovation is not as good a predictor of product innovation outcomes as is the firm’s product innovation orientation (strategy).
|
107 |
The technological imperative of newspaper-publishing companies in Thailand : routine technology and organizational structure /Chaitantipongse, Jirawatana. January 1900 (has links)
Thesis (Ph. D.)--New York University, School of Education, 2005. / Typescript. Includes bibliographical references (leaves 81-86). Also available in electronic format on the World Wide Web. Access restricted to users affiliated with the licensed institutions.
|
108 |
An analytical study of the costs factors involved in inventory controls procurement costs and carrying costsJackson, King S 01 August 1967 (has links)
No description available.
|
109 |
The Impact of Portfolio Disclosure on Hedge Fund Performance, Fees, and FlowsJanuary 2011 (has links)
abstract: This study investigates the impact of portfolio disclosure on hedge fund performance. Using a regression discontinuity design, I investigate the effect of the disclosure requirements that take effect when an investment company's assets exceed $100 million; when that occurs, a fund is required by the SEC to submit form 13F disclosing its portfolio holdings. Consistent with the argument that portfolio disclosure reveals "trade secrets" and also raises front running costs thus harms the funds that disclose, I find that there is a drop in fund performance (about 4% annually) after a fund begins filing form 13F, as well as an increase in return correlations with other hedge funds in the same investment style. The drop in performance cannot be explained by a change in the assets under management or a mean reversion in returns. Consistent with the idea that funds with illiquid holdings tend to employ sequential trading strategies, which increase the likelihood of being taken advantage of by free riders and front runners, the drop in performance is more dramatic for funds that have more illiquid holdings. In addition, I find that the incentive fees paid to fund managers are 1% higher when portfolio disclosure is required, which supports the hypothesis that investors' monitoring of portfolio holdings disciplines adverse risk-taking by fund managers and allows for higher convexity in the optimal compensation structure. Finally, there is a drop in flows into funds that file 13F, which suggests that hedge fund investors negatively value 13F disclosure. Overall, this study suggests that the cost of portfolio disclosure is economically large. It contributes to the policy debate over what constitutes optimal disclosure. / Dissertation/Thesis / Ph.D. Business Administration 2011
|
110 |
A restaurant for the Atlanta University Center -a feasibility studyJarecha, Navin M 01 July 1966 (has links)
No description available.
|
Page generated in 0.064 seconds