Multiple Control Variables Research Articles

Legendre Cooperative PSO Strategies for Trajectory Optimization

Particle swarm optimization (PSO) is a population‐based stochastic optimization technique in a smooth search space. However, in a category of trajectory optimization problem with arbitrary final time and multiple control variables, the smoothness of variables cannot be satisfied since the linear interpolation is widely used. In the paper, a novel Legendre cooperative PSO (LCPSO) is proposed by introducing Legendre orthogonal polynomials instead of the linear interpolation. An additional control variable is introduced to transcribe the original optimal problem with arbitrary final time to the fixed one. Then, a practical fast one‐dimensional interval search algorithm is designed to optimize the additional control variable. Furthermore, to improve the convergence and prevent explosion of the LCPSO, a theorem on how to determine the boundaries of the coefficient of polynomials is given and proven. Finally, in the numeral simulations, compared with the ordinary PSO and other typical intelligent optimization algorithms GA and DE, the proposed LCPSO has traits of lower dimension, faster speed of convergence, and higher accuracy, while providing smoother control variables.

Divestitures and the Financial Conglomerate Excess Value

We study a sample of the world’s largest financial conglomerates from 15 countries and we track their largest divestitures over the period 2005-2016. We develop a novel market-based metric to analyse the impact of divestitures on financial conglomerate excess value, and our findings point to divestitures having a significant impact on financial conglomerate valuation, contributing to a reduced conglomerate discount. Our results are driven by sales of financial service assets. Selling assets unrelated to the financial sector has no significant effect on conglomerate excess value. These results are robust with the inclusion of multiple control variables and alternative econometric model specifications. Altogether these results cast doubts on the existence of large benefits for financial conglomerates from combining financial service activities. This study has implications both for financial conglomerate boards who might direct their strategies to downsize their firms, and for regulators who address issues related to financial stability.

Biomarkers of Inflammation Mediate an Association Between Sexual Activity and Quality of Life in Older Adulthood

BackgroundInflammatory processes underlie biological mechanisms responsible for age-related disease and quality of life. Psychological stress can activate acute-phase reactants associated with inflammation, and sexual activity can assist in the management of stress. AimTo test whether inflammatory biomarkers (C-reactive protein [CRP], fibrinogen, and white blood cell [WBC] count) would mediate an association between frequency of sexual activity and quality of life in older adulthood. MethodsOlder adults from England (N = 4,554; 2,049 men, 2,505 women; mean age = 66.25 ± 8.89 years) provided blood samples and completed self-report questionnaires on sexual activity, quality of life, and health-related behavior. OutcomesCRP (milligrams per liter), fibrinogen (grams per liter), WBC count (109 cells/L), and quality of life (self-report). ResultsFrequency of sexual activity had a negative association with CRP and fibrinogen. An age-moderated effect also showed that frequency of sexual activity had a negative association with WBC count in older participants in the sample (>70 years of age). CRP mediated a positive association between frequency of sexual activity and quality of life. An age-moderated mediation effect also showed that WBC count mediated the association between sexual activity and quality of life in the oldest participants in the sample. All analyses controlled for demographic, anthropometric, and health-related factors. Clinical TranslationMore frequent sexual activity might be a useful auxiliary approach to lowering stress-related inflammation and improving quality of life. Strengths and LimitationsStrengths of this study include the large sample and multiple control variables. Limitations include the cross-sectional nature of the data and some loss in sample representativeness. ConclusionFindings provide evidence that more sexually active older adults exhibit an anti-inflammatory status associated with a perception of higher quality of life. Further research using prospective designs and natural experimental methods is encouraged.Allen MS. Biomarkers of Inflammation Mediate an Association Between Sexual Activity and Quality of Life in Older Adulthood. J Sex Med 2017;14:654–658.

An Adaptive Pseudospectral Method for Constrained Dynamic Optimization Problems in Chemical Engineering

AbstractAn adaptive pseudospectral method with two novel strategies is proposed to solve constrained dynamic optimization problems in chemical engineering. The first strategy is to introduce slope information in designing appropriate subintervals, so that the approach becomes more efficient to track the optimal control profiles. The second strategy is to redistribute the collocation points based on the approximation error, thus ensuring the accuracy of the method. Two constrained dynamic optimization problems with multiple control variables are tested as illustrations, and the proposed approach is compared with other methods. The research results reveal the effectiveness of the proposed method in improving the solution accuracy of dynamic optimization problems.

Evolutionary memetic algorithms supported by metaheuristic profiling effectively applied to the optimization of discrete routing problems

Optimizing the routing of resources to multiple remote sites is a complex issue confronting many sectors of the gas an oil industries with significant cost implications. When significant numbers of sites are involved the optimum solutions become difficult to find and require complex algorithms to do so. Memetic algorithms (MA), combining multiple metaheuristics and heuristics that can be easily activated or deactivated offer a potentially effective and flexible approach to complex routing optimization problems. By combining MAs with the recently proposed tool of metaheuristic profiling (MHP) it is possible to establish and monitor the contributions of the component metaheuristics and heuristics in finding the lowest-distance tour solutions for routing problems. MHP also facilitates the identification of synergies between specific metaheuristics, potential conflicts or duplication among others, and computational time consumption issues with certain combinations. Applying MHP as a monitoring tool during the development of MAs helps to develop balanced algorithms combining multiple metaheuristics focused on specific tasks, such as exploring the global solution space and/or exploiting the space locally around specific solutions. Memetic algorithms make it possible to consider the classic evolutionary algorithms and other well-known heuristics each as components in a “toolbox” of metaheuristics/heuristics available to be combined and configured to form flexible, fit-for-purpose optimization tools. A routing memetic algorithm is described in detail and tested using well-studied examples of the travelling salesman problem (TSP). MHP is applied, using the Excel-VBA platform, to reveal the relative contribution of the nine metaheuristics involved in the routing MA developed here, which incorporates some of the metaheuristics derived from bat-flight principles. The study identifies how these metaheuristics function together with integrational synergies. The MHP information is displayed in graphic and tabular form, alongside the optimum values obtained from multiple executions of the algorithm to illustrate the guidance and level of insight that can be provided by the MHP technique. Memetic algorithms typically involve multiple control variables that can be (and often need to be) tuned to improve their efficiency in finding the optima of specific problems. This makes them flexible, but potentially time consuming to setup and operate. The successful application of the MA to the TSP routing problem suggests scope for its development to address more complex routing problems.

Mapping longitudinal stream connectivity in the North St. Vrain Creek watershed of Colorado

We use reach-scale stream gradient as an indicator of longitudinal connectivity for water, sediment, and organic matter in a mountainous watershed in Colorado. Stream reaches with the highest gradient tend to have narrow valley bottoms with limited storage space and attenuation of downstream fluxes, whereas stream reaches with progressively lower gradients have progressively more storage and greater attenuation. We compared the distribution of stream gradient to stream-reach connectivity rankings that incorporated multiple potential control variables, including lithology, upland vegetation, hydroclimatology, road crossings, and flow diversions. We then assessed connectivity rankings using different weighting schemes against stream gradient and against field-based understanding of relative connectivity within the watershed. We conclude that stream gradient, which is simple to map using publicly available data and digital elevation models, is the most robust indicator of relative longitudinal connectivity within the river network.

Improved multi-objective model predictive control of permanent magnetic synchronous generator wind power system

A novel sorting-based multi-objective model predictive control strategy for controlling converters of permanent magnetic synchronous generator wind turbines is proposed in this paper. To avoid the nontrivial process of scale factors tuning which is typical in traditional multi-objective model predictive control, sorting and ranking is incorporated in this method where quicksort is utilized to sort the multiple control variables with the principle of variable that has smaller objective function value ranking higher. In addition, predictive direct torque control and direct power control are adopted separately for the generator-side and the grid-side converters in which one-step delay in digital implementation and switching losses are compensated without deterioration of system stability. In order to verify the effectiveness of the proposed method, simulations and experimental tests are conducted separately with results showing that the proposed method can get excellent steady and dynamic performance with lowered fluctuations and switching frequencies while avoiding the tedious scale factors tuning process.

Female family caregivers face a higher risk of hypertension and lowered estimated glomerular filtration rates: a cross-sectional, comparative study.

BackgroundDespite societal efforts to alleviate the challenges, caregiving seems to constitute a substantial burden and source of stress for many families of older adults in Japan. However, precise information on the physical health of caregivers, based on objective data, is not available. The purpose of this study was to improve the understanding of the physical health of Japanese family caregivers using objective indicators and a comparative research design.MethodsA cross-sectional, comparative study was conducted among family caregivers and their non-caregiver counterparts. Surveyors visited caregivers in their homes to administer a questionnaire survey, measure their blood pressure, and collect blood samples using a kit. Blood samples were tested for LDL-Cholesterol, HDL-Cholesterol, AST, ALT, γ-GTP, uric acid, creatinine and HbA1c. Non-caregiver data were collected at a university-based health checkup center. We compared 149 caregivers with 149 sex- and age-matched non-caregivers using conditional logistic regression analyses to examine the impact of caregiving, adjusting for multiple control variables. Analyses were conducted separately for men and female.ResultsThe prevalence of high blood pressure was significantly higher among caregivers than non-caregivers (male: 72.7% among caregivers vs. 40.9% among non-caregivers, female: 57.1% vs. 27.6%, respectively). After adjusting for related sociodemographic and health factors, high blood pressure remained significantly more prevalent among caregivers than non-caregivers, only among female (adjusted OR=2.16, 95% CI [1.14, 4.08]). Female caregivers showed lower eGFR than their non-caregiver counterparts (adjusted OR=6.54, 95% CI [2.38, 17.91]). No significant differences were observed between the two groups on any other indicators.ConclusionsResults suggest that female caregivers are at a higher risk of conditions such as cerebral, cardiovascular or kidney diseases than non-caregivers. Steps must be taken to identify caregivers with high blood pressure and lowered eGFR and provide them with the support they need before these risk factors develop into serious diseases.

State Higher Education Performance Funding for Community Colleges: Diverse Effects and Policy Implications

Background/Context Community colleges are central to the United States’ college completion goals. A popular strategy pushed by a number of influential policy organizations and foundations is a policy of tying state funding to community college completions, otherwise known simply as performance funding. This is happening despite little to no evidence that such a strategy actually increases institutional performance. Purpose This study asks: To what extent does the introduction of performance funding programs impact two-year degree completion among participating states? Population/Participants We created a unique panel data set for the period 1990 through 2010, using states as our primary unit of analysis. The data set contains 1,050 total observations, drawing from a range of postsecondary data sources. Research Design We used a quasi-experimental regression technique called difference-indifferences regression technique. We also included in our model multiple control variables and year and state fixed effects. Findings/Results We find that the program had no effect on average and mixed results for the individual states where performance funding was associated with lower completions in six states, greater completions in four states, and inconclusive patterns in nine states. Conclusions We conclude that performance funding is no “silver bullet” for improving community college completions; rather, in some cases, it may interfere with national completion goals. We recommend that state policy makers seek out evidence-based alternatives for improving community college completions.

A fuzzy inexact two-phase programming approach to solving optimal allocation problems in water resources management

Inappropriate agricultural activities are the main reasons of water shortage and environmental pollution in many rural areas. How to generate preferred decision schemes for agricultural activities is a critical issue for decision makers. In this study, a two-phase programming approach is advanced for regional water resources allocation in a rural region of China. The approach shows applicability when the uncertain inputs are provided as intervals and such uncertainty is desired to be delivered to the corresponding solutions. Multiple control variables are introduced both in the objective function and constraints of the programming model, which make it possible for the constraints being relaxed under respective levels. A more satisfactory objective value can thus be expected as well as the impact of each constraint on the modeling outputs can be clarified effectively. The decision variables are useful for decision makers to justify and/or adjust the decision schemes for agricultural activities through incorporation of their implicit knowledge on water allocation management.

Prevention of Leptospirosis Infected Vector and Human Population by Multiple Control Variables

Leptospirosis is an infectious disease that damages the liver and kidneys, found mainly in dogs and farm animals and caused by bacteria. In this paper, we present the optimal control problem applied to a dynamical leptospirosis infected vector and human population by using multiple control variables. First, we show the existence of the control problem and then use analytical and numerical techniques to investigate the existence cost effective control efforts for prevention of indirect and direct transmission of this disease. In order to do this, we consider three control functions two for human and one for vector population. We completely characterize the optimal control problem and compute the numerical solution of the optimality system using an iterative method.

Inexact two-phase fuzzy programming and its application to municipal solid waste management

In this study, an inexact two-phase fuzzy programming approach was proposed for municipal solid waste management. Through introducing multiple control variables, objective function and constraints of the management model were relaxed under different levels, and compromised decision schemes with a high satisfactory level can be expected. Compared to the previous studies, it showed sound capability in identifying key factors and/or input conditions that may significantly affect system outputs, and thus facilitating the decision maker adjusting current system status to benefit the future management. A MSW management problem was provided to demonstrate the performance of the approach. Special parameters having significant or no impact on system performance were specified, which were then respectively changed to constitute two scenarios. The scenario analysis proved the accuracy of the model in identifying key factors. It was also found that the average satisfactory level of optimal solutions from the two-phase model was [0.287, 0.829], which was higher than that obtained from the conventional approach (i.e. [0.130, 0.804]), indicating the advantage of the proposed approach in searching for optimal solutions with high satisfactory level.

U.S. Troops and Foreign Economic Growth

Do American troops help or hinder economic growth in other countries? We consider a newly constructed dataset of the deployment of U.S. troops over the years 1950–2000 and discover a positive relationship between deployed troops and host country economic growth, which is robust to multiple control variables. Each tenfold increase in U.S. troops is associated with a one–third percentage point increase in average host country annual growth. We explore three possible causal explanations: a Keynesian aggregate demand boost; the diffusion of institutions; and security. Extensive econometric testing, including the use of panel data, confirms the core relationship.

CONTROLE MÚLTIPLO NO COMPORTAMENTO VERBAL: HUMOR BRASILEIRO E OPERANTES RELACIONADOS

O presente texto apresenta a formulação de Skinner (1957) a respeito das variáveis responsáveis por aquilo que é compreendido como humor, com exemplos relacionados à literatura e cultura brasileiras. O comportamento responsável por produzir efeitos humorísticos sobre o ouvinte é entendido como sendo passível de controle múltiplo. Esse comportamento é analisado através de seus produtos, como textos e amostras de linguagem falada, sendo possível fazer inferências a respeito das condições nas quais o comportamento ocorreu. Trocadilhos e piadas são exemplos de controle múltiplo dado que: 1) a força de uma determinada resposta é função de mais de uma variável, uma forma de controle múltiplo convergente; 2) uma única variável geralmente afeta mais de uma resposta, uma forma de controle múltiplo divergente. O controle múltiplo pode envolver uma palavra ou frase que está sob controle de pelo menos duas variáveis, ou “fontes” ao mesmo tempo. A palavra ou frase é denominada resposta crítica e as variáveis controladoras são consideradas fontes temáticas principais, fontes secundárias e fontes transportadoras. Através de diferentes exemplos, os três tipos de fontes e o conceito de resposta crítica são descritos, e sao apresentadas sugestões para a criação e análise de um trocadilho bom ou engraçado. A sátira e a ironia são apresentadas como exemplos de comportamentos controlados por audiências distintas, e poemas de Manuel Bandeira são usados para ilustrar o comportamento satírico. Argumenta-se que fazer humor é aprendido e possivelmente um comportamento adaptativo, na medida que um evento pode ser menos estressante se levado com um senso de humor. Palavras-chave: humor, comportamento verbal, controle múltiplo

Optimal Campaign in Leptospirosis Epidemic by Multiple Control Variables

In this paper, we consider a leptospirosis epidemic model to implement optimal campaign by using multiple control variables. First, we show the existence of the control problem. Then we derive the conditions under which it is optimal to eradicate the leptospirosis infection and examine the impact of a possible educatioal/vaccinaction campaign using Pontryagin’s Maximum Principle. We completely characterize the optimal control problem and compute the numerical solution of the optimality system using an iterative method. The results obtained from the numerical simulations of the model show that a possible educational/vaccinaction combined with effective treatment regime would reduce the spread of the leptospirosis infection appreciably.

Interfirm IT Capability Profiles and Communications for Cocreating Relational Value: Evidence from the Logistics Industry

This study seeks to identify the means by which information technology helps cocreate relational value in the context of interfirm relationships in the logistics industry--a large and information-intensive industry. We identify a set of IT functionalities--single-location shipping, multilocation shipping, supply chain visibility, and financial settlement--that can be used to manage the flows of physical goods, information, and finances across locations in interfirm logistics processes. Progressively more advanced sets of IT functionalities, when implemented and used in the interfirm relationship to execute logistics processes, are proposed to form four distinct IT capability profiles of increased sophistication. Interfirm IT capability profiles of higher sophistication are proposed to help cocreate greater relational value by facilitating the flows of physical goods, information, and finances across locations in the interfirm logistics process. Besides their direct role in helping cocreate relational value, these interfirm IT capability profiles are proposed to further enhance relational value cocreation when complemented by interfirm communications for business development and IT development. Our empirical study was situated in one of the world's largest logistics suppliers and over 2,000 of its interfirm relationships with buyers across industries. Integrated data from four archival sources on the IT functionalities implemented and used in interfirm logistics relationships, interfirm communications, relational value (share of wallet and loyalty), and multiple control variables were collected. The results show that the proposed interfirm IT capability profiles and interfirm communications have both a direct and an interaction effect on relational value. Implications for cocreating relational value in interfirm relationships with the aid of IT are discussed.

A Two-Phase Semi-Infinite Programming Method for Yongxin Water Resources Allocation in Jiangxi Province

Inappropriate agricultural activities are the main sources of water shortage to surface and ground water in rural areas. How to generate preferred decision schemes for agricultural activities is a critical issue for decision makers. In this study, a two-phase semi-infinite programming method (TPSIP) is proposed and applied to regional water resource allocations in the County of Yongxin. Multiple control variables are introduced both in the objective function and constraints. This makes it possible for the constraints to be relaxed under respective levels. Thus a more satisfactory objective value can be obtained.

Development of an inexact fuzzy flexible programming approach for environmental pollution control

Optimization techniques have been widely applied to solving environmental management problems, particularly for regional air quality management systems where potential air pollutions arising from improper management would seriously threaten human health. An inexact fuzzy flexible programming approach is developed to facilitate decision support for air quality management. It can tackle both stipulation uncertainty and parameter uncertainty in the objective function and constraints. Upon the previous research efforts, the most significant improvement of this approach is the introduction of multiple control variables corresponding to the objective function and all constraints. This attempt makes it possible for the constraints to be relaxed under respective levels, such that a more satisfactory objective value may be obtained. The impact of each constraint on the system outputs can also be further interpreted. The proposed approach would be helpful for such systems where the decision makers prefer to not only find out an air pollution control scheme with a satisfaction level as high as possible, but also mitigate the uncertainty in decision making. A regional air pollution control problem is then studied to demonstrate the applicability of the developed approach. A variety of management strategies for air pollutants allocation and treatment are suggested in terms of the optimal solutions to decision variables. Comparison between the optimal solutions from the proposed approach and those from a conventional fuzzy flexible programming model is undertaken. It can be found that neither the management strategies nor the priorities of pollutants allocation obtained from the two models are the same. The satisfaction level of the proposed approach (taking the average value of optimized solutions of control variables for comparison) is always higher than that of the existing approach, indicating the superiority of the proposed approach in handling many air pollution control problems.

The relationship between knowledge of HIV, self-perceived vulnerability and sexual risk behavior among community clinic workers in Chile

Testing the hypothesis of an association between knowledge and sexual risk behaviour (SRB) amongst community-clinic workers in Chile, explained by the confounding effect of self-perceived vulnerability to HIV. A cross-sectional survey was analyzed; it was nested within a quasi-experimental study of 720 community-clinic workers in Santiago. The SRB score combined the number of sexual partners and condom use (coded as "high"/"low" SRB). Knowledge of HIV (a 25-item index) was coded as "inadequate"/"adequate" knowledge. Self-perceived vulnerability to HIV was categorised as being "high"/ "moderate"/"low". Control variables included socio-demographics, religiousness and educational level. Percentages/averages, Chi-square tests and logistic regression (OR-estimations) were used for descriptive, association and confounding analysis. Respondents were 78.2 % female, 46.8 % married and 67.6 % Catholic. Mean age was 38.9 (10.5 SD) and 69 % had university/diploma level. Self-perceived HIV vulnerability was "low" in 71.5 % cases. A negative association between knowledge and SRB was found (OR=0.55;CI=0.35-0.86), but self-perceived vulnerability did not have a confounding effect on this relationship. This relationship also persisted after being adjusted for multiple control variables (e.g. age, sex, type of primary centre, educational level, and religiousness). Some community-clinic workers had inaccurate knowledge of HIV, which was associated with SRB. Self-perceived vulnerability did not have a confounding effect; however, future studies should further analyze occupational risk of HIV as a possible driving factor in health workers' perception of their risk. Focused training programmes should be developed to enhance basic knowledge of HIV in this group.

Assessing the cumulative impact of alcohol marketing on young people's drinking: Cross-sectional data findings

As alcohol marketing remains a highly debated and politically charged issue, we examine the cumulative impact of alcohol marketing on alcohol initiation and drinking behaviour among youth (12–14 years). Cross-sectional data come from a cohort of 920 second year school pupils from Scotland. Regression models, with multiple control variables, were employed to examine the relationship between awareness of, and involvement with, a range of alcohol marketing communications, and drinking behaviour and intentions. Marketing variables were constructed for 15 different types of alcohol marketing, including marketing in new media. Drinking behaviour measures included drinking status and future drinking intentions. Significant associations were found between awareness of, and involvement with, alcohol marketing and drinking behaviour and intentions to drink alcohol in the next year. Given these associations, our study suggests the need for a revision of alcohol policy: one limiting youth exposure to these seemingly ubiquitous marketing communications.