Showing papers by "Illinois Institute of Technology published in 2007"

Stochastic Security-Constrained Unit Commitment

Abstract: This paper presents a stochastic model for the long-term solution of security-constrained unit commitment (SCUC). The proposed approach could be used by vertically integrated utilities as well as the ISOs in electricity markets. In this model, random disturbances, such as outages of generation units and transmission lines as well as load forecasting inaccuracies, are modeled as scenario trees using the Monte Carlo simulation method. For dual optimization, coupling constraints among scenarios are relaxed and the optimization problem is decomposed into deterministic long-term SCUC subproblems. For each deterministic long-term SCUC, resource constraints represent fuel and emission constraints (in the case of vertically integrated utilities) and energy constraints (in the case of electricity markets). Lagrangian relaxation is used to decompose subproblems with long-term SCUC into tractable short-term MIP-based SCUC subproblems without resource constraints. Accordingly, penalty prices (Lagrangian multipliers) are signals to coordinate the master problem and small-scale subproblems. Computational requirements for solving scenario-based optimization models depend on the number of scenarios in which the objective is to minimize the weighted-average generation cost over the entire scenario tree. In large scale applications, the scenario reduction method is introduced for enhancing a tradeoff between calculation speed and accuracy of long-term SCUC solution. Numerical simulations indicate the effectiveness of the proposed approach for solving the stochastic security-constrained unit commitment

Concentration dependence of the collective dynamics of swimming bacteria.

Abstract: At concentrations near the maximum allowed by steric repulsion, swimming bacteria form a dynamical state exhibiting extended spatiotemporal coherence. The viscous fluid into which locomotive energy of individual microorganisms is transferred also carries interactions that drive the coherence. The concentration dependence of correlations in the collective state is probed here with a novel technique that herds bacteria into condensed populations of adjustable concentration. For the particular thin-film geometry employed, the correlation lengths vary smoothly and monotonically through the transition from individual to collective behavior.

Emission of coherent THz radiation from superconductors.

Abstract: Compact solid-state sources of terahertz (THz) radiation are being sought for sensing, imaging, and spectroscopy applications across the physical and biological sciences. We demonstrate that coherent continuous-wave THz radiation of sizable power can be extracted from intrinsic Josephson junctions in the layered high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8 . In analogy to a laser cavity, the excitation of an electromagnetic cavity resonance inside the sample generates a macroscopic coherent state in which a large number of junctions are synchronized to oscillate in phase. The emission power is found to increase as the square of the number of junctions reaching values of 0.5 microwatt at frequencies up to 0.85 THz, and persists up to ∼50 kelvin. These results should stimulate the development of superconducting compact sources of THz radiation.

On choosing “optimal” shape parameters for RBF approximation

Abstract: Many radial basis function (RBF) methods contain a free shape parameter that plays an important role for the accuracy of the method. In most papers the authors end up choosing this shape parameter by trial and error or some other ad hoc means. The method of cross validation has long been used in the statistics literature, and the special case of leave-one-out cross validation forms the basis of the algorithm for choosing an optimal value of the shape parameter proposed by Rippa in the setting of scattered data interpolation with RBFs. We discuss extensions of this approach that can be applied in the setting of iterated approximate moving least squares approximation of function value data and for RBF pseudo-spectral methods for the solution of partial differential equations. The former method can be viewed as an efficient alternative to ridge regression or smoothing spline approximation, while the latter forms an extension of the classical polynomial pseudo-spectral approach. Numerical experiments illustrating the use of our algorithms are included.

Modeling and Simulation of Electric and Hybrid Vehicles

Abstract: This paper discusses the need for modeling and simulation of electric and hybrid vehicles. Different modeling methods such as physics-based Resistive Companion Form technique and Bond Graph method are presented with powertrain component and system modeling examples. The modeling and simulation capabilities of existing tools such as Powertrain System Analysis Toolkit (PSAT), ADvanced VehIcle SimulatOR (ADVISOR), PSIM, and Virtual Test Bed are demonstrated through application examples. Since power electronics is indispensable in hybrid vehicles, the issue of numerical oscillations in dynamic simulations involving power electronics is briefly addressed

Self-efficacy and empowerment as outcomes of self-stigmatizing and coping in schizophrenia

Abstract: The concept of internalized stigma or self-stigma is central to the understanding of the psychological harm caused by stigma. In this study, we aim to demonstrate how the evaluative dimension of self-concept (self-efficacy and empowerment) mediates the psychological effects of self-stigmatizing and coping with stigma. As important examples of psychological effects, depression and quality of life were focussed on. In 172 outpatients with DSM-IV schizophrenia, measures of self-stigma and devaluation, coping with stigma, self-efficacy, empowerment, quality of life and depression were assessed. It was hypothesized that withdrawal and secrecy as important coping strategies yielded to higher levels of anticipatory anxiety of future stigmatizing. Higher levels of perceived discrimination and devaluation were hypothesised to undermine self-efficacy and illness-related empowerment. Lowering of empowerment was supposed to enhance depression and reduce quality of life. This hypothesis was tested by Structural Equation Modeling as a method of data analysis. The results supported the hypothesized model; i.e., 46% of depression and 58% of quality of life reduction could be explained by eroded empowerment. Moreover, 51% of the empowerment reduction was explained by reduction in self-efficacy at a more general level by dysfunctional coping and higher levels of anticipated stigma. Taken together, our data suggest an avoidant coping style as a risk factor for anticipatory stigma, which erodes self-efficacy and empowerment. These data have implications for cognitive behavioral approaches, which should focus on anticipated stigma to improve recovery in schizophrenia.

Repeatable evaluation of search services in dynamic environments

Abstract: In dynamic environments, such as the World Wide Web, a changing document collection, query population, and set of search services demands frequent repetition of search effectiveness (relevance) evaluations. Reconstructing static test collections, such as in TREC, requires considerable human effort, as large collection sizes demand judgments deep into retrieved pools. In practice it is common to perform shallow evaluations over small numbers of live engines (often pairwise, engine A vs. engine B) without system pooling. Although these evaluations are not intended to construct reusable test collections, their utility depends on conclusions generalizing to the query population as a whole. We leverage the bootstrap estimate of the reproducibility probability of hypothesis tests in determining the query sample sizes required to ensure this, finding they are much larger than those required for static collections. We propose a semiautomatic evaluation framework to reduce this effort. We validate this framework against a manual evaluation of the top ten results of ten Web search engines across 896 queries in navigational and informational tasks. Augmenting manual judgments with pseudo-relevance judgments mined from Web taxonomies reduces both the chances of missing a correct pairwise conclusion, and those of finding an errant conclusion, by approximately 50p.

How Clinical Diagnosis Might Exacerbate the Stigma of Mental Illness

Abstract: Stigma can greatly exacerbate the experience of mental illness. Diagnostic classification frequently used by clinical social workers may intensify this stigma by enhancing the public's sense of "groupness" and "differentness" when perceiving people with mental illness. The homogeneity assumed by stereotypes may lead mental health professionals and the public to view individuals in terms of their diagnostic labels. The stability of stereotypes may exacerbate notions that people with mental illness do not recover. Several strategies may diminish the unintended effects of diagnosis. Dimensional approaches to diagnosis may not augment stigma in the same manner as classification. Moreover, regular interaction with people with mental illness and focusing on recovery may diminish the stigmatizing effects of diagnosis.

The Stigma of Psychiatric Disorders and the Gender, Ethnicity, and Education of the Perceiver

Abstract: The purpose of this study is to determine how the demographics of perceivers influence their stigma of people with mental illness or with substance abuse. A nationally representative sample (N = 968) was asked to respond to a vignette describing a person with a health condition (schizophrenia, drug dependence, or emphysema) and his/her family member. Consistent with our hypotheses, women were less likely to endorse stigma than men. Participants with higher education were also less likely to stigmatize than less educated participants. Contrary to our expectations, nonwhite research participants were more likely to endorse stigma than whites. Implications of these findings for better understanding the stigma of mental illness, and the development of anti-stigma programs, are reviewed.

User Value: Competing Theories and Models

Abstract: In design research, the issues of what exactly constitutes user value and how design can contribute to its creation are not commonly discussed. This paper provides a critical overview of the theories of value used in anthropology, sociology, philosophy, business, and economics. In doing so, it reviews a range of theoretical and empirical studies, with particular emphasis on their position on product, user, and designer in the process of value creation. The paper first looks at the similarities and differences among definitions of value as exchange, sign, and experience. It then reviews types and properties of user value such as its multidimensionality, its contextuality, its interactivity, and the stages of user experience dependency identified by empirical studies. Methodological approaches to user value research and their possible applications in design are also discussed. Finally, directions for future research on user value are discussed giving particular emphasis to the need of tools and methods to support design practice.

Approach to an asymptotic state for zero pressure gradient turbulent boundary layers

Abstract: Flat plate turbulent boundary layers under zero pressure gradient at high Reynolds numbers are studied to reveal appropriate scale relations and asymptotic behaviour. Careful examination of the skin-friction coefficient results confirms the necessity for direct and independent measurement of wall shear stress. We find that many of the previously proposed empirical relations accurately describe the local Cf behaviour when modified and underpinned by the same experimental data. The variation of the integral parameter, H, shows consistent agreement between the experimental data and the relation from classical theory. In accordance with the classical theory, the ratio of D and d asymptotes to a constant. Then, the usefulness of the ratio of appropriately defined mean and turbulent time-scales to define and diagnose equilibrium flow is established. Next, the description of mean velocity profiles is revisited, and the validity of the logarithmic law is re-established using both the mean velocity profile and its diagnostic function. The wake parameter, P, is shown to reach an asymptotic value at the highest available experimental Reynolds numbers if correct values of logarithmic-law constants and an appropriate skin-friction estimate are used. The paper closes with a discussion of the Reynolds number trends of the outer velocity defect which are important to establish a consistent similarity theory and appropriate scaling.

Target-Oriented Scheduling in Directional Sensor Networks

Abstract: Unlike convectional omni-directional sensors that always have an omni-angle of sensing range, directional sensors may have a limited angle of sensing range due to technical constraints or cost considerations. A directional sensor network consists of a number of directional sensors, which can switch to several directions to extend their sensing ability to cover all the targets in a given area. Power conservation is still an important issue in such directional sensor networks. In this paper, we address the multiple directional cover sets problem (MDCS) of organizing the directions of sensors into a group of non-disjoint cover sets to extend the network lifetime. One cover set, in which the directions cover all the targets, is activated at one time. We prove the MDCS to be NP-complete and propose three heuristic algorithms for the MDCS. Simulation results are also presented to demonstrate the performance of these algorithms.

Market-Based Coordination of Transmission and Generation Capacity Planning

Abstract: We propose an ISO model for coordinating transmission expansion planning with competitive generation capacity planning in electricity markets. The purpose of the model is a holistic simulation of generation and transmission capacity expansion in the market environment. The solution represents an iterative process for simulating the interactions among GENCOs, TRANSCOs, and the ISO, which might be terminated by the ISO based on a pre-specified stopping criterion. The proposed model adopts a joint energy and transmission auction market and a capacity mechanism. The joint auction market enables competition to occur among generation and transmission resources. The capacity mechanism offers incentives for market participant investments that reflect the locational values of additional capacity. Transmission capacity expansion decisions are made by merchant transmission lines that recover their capacity investments through transmission marginal pricing and capacity payments. Transmission network security is reflected in the proposed competitive resource planning model. The examples illustrate a coordinated planning of generation and transmission in restructured power systems.

Measuring Self-Stigma of Mental Illness in China and Its Implications for Recovery

Abstract: This study translated and validated the Chinese Version of the Self-stigma of Mental Illness Scale (CSSMIS), which may be used to measure self-stigma of mental health consumers in China. We also examined its correlation with self-esteem, self-efficacy and psychosocial treatment compliance. A cross-sectional observational study was implemented. Some 51 males and 57 females who suffered from severe mental illness were recruited from psychiatric settings in Hong Kong. They were required to complete the Chinese Version of the Self-stigma of Mental Illness Scale, the Rosenberg Self-esteem Scale and the Self-efficacy Scale. Their level of compliance during psychosocial treatment and their demographic information were recorded by their case managers. Exploratory factor analysis revealed two homologous factors for the four subscales of the CSSMIS. Factor 1 was related to the negative beliefs and consequences of having mental disorders, whereas Factor 2 was related to positive beliefs. The perceived stigma subscale and the three self-stigma subscales were strongly inter-correlated. Significant correlations were also found between almost all subscales of the CSSMIS and the remaining scales. The psychometric properties of the CSSMIS are statistically acceptable. The results also suggest that stigma played a detrimental role in undermining self-esteem, self-efficacy and psychosocial treatment compliance. Implications for recovery of mental health consumers are discussed.

Clioquinol, a Therapeutic Agent for Alzheimer's Disease, Has Proteasome-Inhibitory, Androgen Receptor–Suppressing, Apoptosis-Inducing, and Antitumor Activities in Human Prostate Cancer Cells and Xenografts

Abstract: Tumor growth and metastasis depend on angiogenesis that requires the cofactor copper. Consistently, high levels of copper have been found in many types of human cancers, including prostate, breast, colon, and lung. Recent studies suggest that copper could be used as a novel selective target for cancer therapies. Clioquinol is capable of forming stable complexes with copper and currently used in clinics for treatment of Alzheimer's disease. Most recently, it has been reported that clioquinol possesses antitumor effects. However, the underlying molecular mechanism is unclear. We report here that after binding to copper, clioquinol can inhibit the proteasomal chymotrypsin-like activity, repress androgen receptor (AR) protein expression, and induce apoptotic cell death in human prostate cancer LNCaP and C4-2B cells. In addition, clioquinol alone exhibits similar effects in prostate cancer cell lines with elevated copper at concentrations similar to those found in patients. Addition of dihydrotestosterone did not affect clioquinol-mediated proteasome inhibition in both prostate cancer cell lines. However, dihydrotestosterone partially inhibited clioquinol-induced AR suppression and apoptosis only in androgen-dependent LNCaP cells. Animal studies show that clioquinol treatment significantly inhibits the growth of human prostate tumor C4-2B xenografts (by 66%), associated with in vivo proteasome inhibition, AR protein repression, angiogenesis suppression, and apoptosis induction. Our study provides strong evidence that clioquinol is able to target tumor proteasome in vivo in a copper-dependent manner, resulting in formation of an active AR inhibitor and apoptosis inducer that is responsible for its observed antiprostate tumor effect.

Comprehensive Efficiency Modeling of Electric Traction Motor Drives for Hybrid Electric Vehicle Propulsion Applications

Abstract: Extensive research done in the recent past has proven that power electronic converters and electric propulsion motors are extremely critical components for modern hybrid electric vehicle (HEV) propulsion applications. Therefore, it is essential that both the traction motor and the associated drive operate at their optimal efficiencies throughout the driving schedule. In typical HEV propulsion applications, the traction motor and the drive are used over the entire torque/speed operational range. In view of this fact, this paper aims at modeling the inverter and motor losses/efficiencies over typical city and highway driving schedules. The noteworthy losses within a typical three-phase dc/ac traction inverter, such as the switching and conduction losses for both the insulated-gate bipolar transistors and the antiparallel diodes, are modeled and simulated over the city and highway driving patterns. An induction motor (IM) is used for a medium-sized sport utility vehicle, which was modeled in the advanced vehicle simulator (ADVISOR) software. The significant IM losses that were considered in the study include the stator copper losses, rotor copper losses, and core losses. Thus, the average efficiencies of both the inverter drive and the induction traction motor are evaluated and summarized under city as well as highway driving conditions. Finally, based on the individual-model-based efficiency analysis, the overall traction motor drive system efficiency is estimated.

Maximizing a Submodular Set Function Subject to a Matroid Constraint (Extended Abstract)

Abstract: Let $f:2^{N} \rightarrow \cal R^{+}$ be a non-decreasing submodular set function, and let $(N,\cal I)$ be a matroid. We consider the problem $\max_{S \in \cal I} f(S)$. It is known that the greedy algorithm yields a 1/2-approximation [9] for this problem. It is also known, via a reduction from the max-k-cover problem, that there is no (1 i¾? 1/e+ i¾?)-approximation for any constant i¾?> 0, unless P= NP[6]. In this paper, we improve the 1/2-approximation to a (1 i¾? 1/e)-approximation, when fis a sum of weighted rank functions of matroids. This class of functions captures a number of interesting problems including set coverage type problems. Our main tools are the pipage rounding technique of Ageev and Sviridenko [1] and a probabilistic lemma on monotone submodular functions that might be of independent interest. We show that the generalized assignment problem (GAP) is a special case of our problem; although the reduction requires |N| to be exponential in the original problem size, we are able to interpret the recent (1 i¾? 1/e)-approximation for GAP by Fleischer et al.[10] in our framework. This enables us to obtain a (1 i¾? 1/e)-approximation for variants of GAP with more complex constraints.

Measurement of neutrino velocity with the MINOS detectors and NuMI neutrino beam

Abstract: The velocity of a similar to 3 GeV neutrino beam is measured by comparing detection times at the near and far detectors of the MINOS experiment, separated by 734 km. A total of 473 far detector neutrino events was used to measure (nu - c)/c=5.1 +/- 2.9 x 10(-5) (at 68% C.L.). By correlating the measured energies of 258 charged-current neutrino events to their arrival times at the far detector, a limit is imposed on the neutrino mass of m(nu)50 MeV/c(2) (99% C.L.).

Risk-Constrained Bidding Strategy With Stochastic Unit Commitment

Abstract: This paper develops optimal bidding strategies based on hourly unit commitment in a generation company (GENCO) that participates in energy and ancillary services markets. The price-based unit commitment problem with uncertain market prices is modeled as a stochastic mixed integer linear program. The market price uncertainty is modeled using the scenario approach, Monte Carlo simulation is applied to generate scenarios, scenario reduction techniques are applied to reduce the size of the stochastic price-based unit commitment problem, and postprocessing is applied based on marginal cost of committed units to refine bidding curves. The financial risk associated with market price uncertainty is modeled using expected downside risk, which is incorporated explicitly as a constraint in the problem. Accordingly, the proposed method provides a closed-loop solution to devising specific strategies for risk-based bidding in a GENCO. Illustrative examples show the impact of market price uncertainty on GENCO's hourly commitment schedule and discuss the way GENCOs could decrease financial risks by managing expected payoffs

Stylistic text classification using functional lexical features

Abstract: Most text analysis and retrieval work to date has focused on the topic of a text; that is, what it is about. However, a text also contains much useful information in its style, or how it is written. This includes information about its author, its purpose, feelings it is meant to evoke, and more. This article develops a new type of lexical feature for use in stylistic text classification, based on taxonomies of various semantic functions of certain choice words or phrases. We demonstrate the usefulness of such features for the stylistic text classification tasks of determining author identity and nationality, the gender of literary characters, a text’s sentiment (positive/ negative evaluation), and the rhetorical character of scientific journal articles. We further show how the use of functional features aids in gaining insight about stylistic differences among different kinds of texts.

On Broadcast Authentication in Wireless Sensor Networks

Abstract: Broadcast authentication is a critical security service in wireless sensor networks (WSNs), since it enables users to broadcast the WSN in an authenticated way. Symmetric key based schemes such as muTESLA and multilevel muTESLA have been proposed to provide such services for WSNs; however, these schemes all suffer from serious DoS attacks due to the delay in message authentication. This paper presents several effective public key based schemes to achieve immediate broadcast authentication and thus overcome the vulnerability presented in the muTESLA-like schemes. Several cryptographic techniques, including Merkle hash tree and identity-based signature scheme, are adopted to minimize the scheme overhead regarding the costs on both computation and communication. A quantitative energy consumption analysis of the proposed schemes is given in detail. We believe that this paper can serve as the start point towards fully solving the important multisender broadcast authentication problem in WSNs.

Hand Rehabilitation Following Stroke: A Pilot Study of Assisted Finger Extension Training in a Virtual Environment

Abstract: Background and Purpose: The purpose of this pilot study was to investigate the impact of assisted motor training in a virtual environment on hand function in stroke survivors. Participants: Fifteen volunteer stroke survivors (32‐88 years old) with chronic upper extremity hemiparesis (1‐38 years post incident) took part. Method: Participants had 6 weeks of training in reach-to-grasp of virtual and actual objects. They were randomized to one of three groups: assistance of digit extension provided by a novel cable orthosis, assistance provided by a novel pneumatic orthosis, or no assistance provided. Hand performance was evaluated at baseline, immediately following training, and 1 month after completion of training. Clinical assessments included the Wolf Motor Function Test (WMFT), Box and Blocks Test (BB), Upper Extremity Fugl-Meyer Test (FM), and Rancho Los Amigos Functional Test of the Hemiparetic Upper Extremity (RLA). Biomechanical assessments included grip strength, extension range of motion and velocity, spasticity, and isometric strength. Results: Participants demonstrated a significant decrease in time to perform functional tasks for the WMFT (p = .02), an increase in the number of blocks successfully grasped and released during the BB (p = .09), and an increase for the FM score (p = .08). There were no statistically significant changes in time to complete tasks on the RLA or any of the biomechanical measures. Assistance of extension did not have a significant effect. Discussion and Conclusion: After the training period, participants in all 3 groups demonstrated a decrease in time to perform some of the functional tasks. Although the overall gains were slight, the general acceptance of the novel rehabilitation tools by a population with substantial impairment suggests that a larger randomized

Will filmed presentations of education and contact diminish mental illness stigma

Abstract: This study examines the impact of two versions of anti-stigma programs-education and contact-presented on videotape. A total of 244 people were randomly assigned to education or contact conditions and completed pre-test, post-test, and follow-up measures of stereotypes. Results suggest that the education videotape had limited effects, mostly showing improvement in responsibility (people with mental illness are not to blame for their symptoms and disabilities). Watching the contact videotaped showed significant improvement in pity, empowerment, coercion, and segregation. Contact effects were evident at post-test and 1 week follow-up. Implications of these findings for future research are discussed.

Load balancing for cellular/WLAN integrated networks

Abstract: The interworking between heterogeneous third-generation cellular networks and wireless local area networks is one promising evolution approach to fourth-generation wireless networks, which can exploit the complementary advantages of the cellular network and WLANs. Resource management for the 4G-oriented cellular/WLAN integrated network is an important open issue that deserves more research efforts. In this article we present a policy framework for resource management in a loosely coupled cellular/WLAN integrated network, where load balancing policies are designed to efficiently utilize the pooled resources of the network. A two-phase control strategy is adopted in the load balancing policies, in which call assignment is used to provide a statistical quality of service guarantee during the admission phase, and dynamic vertical handoff during the traffic service phase is used to minimize the performance variations. Numerical results are presented to demonstrate that the proposed load balancing solution achieves significant performance improvement over two other reference schemes

Principles and Practice of Psychiatric Rehabilitation : An Empirical Approach

Abstract: Part I: Introduction. Who Are People with Psychiatric Disabilities? Stigma and Mental Illness. Definition of Psychiatric Rehabilitation. Part II: Service Approaches. Rehabilitation Assessment. Illness Self-management. Case Management. Medications and Psychiatric Rehabilitation. Housing. Employment and Education. Social Functioning. Family Interventions. Psychosis and Cognitive Impairment. Managing Criminal Justice Involvement. Part III: Special Populations and Problems. Trauma and Posttraumatic Stress Disorder. Dual Diagnosis. Physical Health and Medical Care. Peer Services and Supports. Managing Aggressive Behavior. Part IV: System Considerations. Erasing Stigma and Promoting Empowerment. Cultural Competence in Psychiatric Rehabilitation. Policy.

A Novel Digital Control Technique for Brushless DC Motor Drives

Abstract: Brushless DC (BLDC) motor drives are continually gaining popularity in motion control applications. Therefore, it is necessary to have a low cost, but effective BLDC motor speed/torque regulator. This paper introduces a novel concept for digital control of trapezoidal BLDC motors. The digital controller was implemented via two different methods, namely conduction-angle control and current-mode control. Motor operation is allowed only at two operating points or states. Alternating between the two operating points results in an average operating point that produces an average operating speed. The controller design equations are derived from Newton's second law. The novel controller is verified via computer simulations and an experimental demonstration is carried out with the rapid prototyping and real-time interface system dSPACE.