Active Control Effort Research Articles

A hybrid clustering-based type-2 adaptive neuro-fuzzy forecasting model for smart control systems

The practical applicability of smart control systems suffers from the existence of uncertainty in the physical parameters, sensor measurements and external excitations. Effective methods and its ease of implementation are required in the real-time active control strategies. To this end, in this research, we introduce an overlapping clusters and Multilayer Extreme Learning Machine (ML-ELM)-aided interval type-2 Takagi-Sugeno fuzzy inference system for vibration mitigation of smart structures. The combined Fuzzy C-Means (FCM) and imperialist competitive algorithm (ICA) with respect to degree of fuzzy overlap between clusters was utilized for characterizing the upper and lower membership functions forming the antecedent part. Furthermore, indeterminacy was modeled as footprint of uncertainty (FOU) and automatically formed based on statistical characteristics of soft clusters. The consequent parameters were adjusted by hybridization of ML-ELM and overlapping clusters, then the adaptivity was guaranteed. The predictive accuracy and generalization capability of the proposed method were demonstrated over the estimation of active control effort. Finally, to prove the practicability of the implemented framework, it was applied to four high-rise, mid-rise and low-rise benchmark building structures equipped with active mass damper (AMD), active tendon and active bracing system (ABS). The obtained results demonstrated the higher predictive accuracy and generalization ability of the presented data-driven control scheme compared to the other standard technical machine learning strategies. This practical guideline is easy to implement and automates control engineering tasks in real-time applications, solving one of the most challenging aspects of smart control systems.

Dynamics of data availability in disease modeling: An example evaluating the trade-offs of ultra-fine-scale factors applied to human West Nile virus disease models in the Chicago area, USA.

BackgroundSince 1999, West Nile virus (WNV) has moved rapidly across the United States, resulting in tens of thousands of human cases. Both the number of human cases and the minimum infection rate (MIR) in vector mosquitoes vary across time and space and are driven by numerous abiotic and biotic forces, ranging from differences in microclimates to socio-demographic factors. Because the interactions among these multiple factors affect the locally variable risk of WNV illness, it has been especially difficult to model human disease risk across varying spatial and temporal scales. Cook and DuPage Counties, comprising the city of Chicago and surrounding suburbs, experience some of the highest numbers of human neuroinvasive cases of WNV in the United States. Despite active mosquito control efforts, there is consistent annual WNV presence, resulting in more than 285 confirmed WNV human cases and 20 deaths from the years 2014–2018 in Cook County alone.MethodsA previous Chicago-area WNV model identified the fifty-five most high and low risk locations in the Northwest Mosquito Abatement District (NWMAD), an enclave ¼ the size of the combined Cook and DuPage county area. In these locations, human WNV risk was stratified by model performance, as indicated by differences in studentized residuals. Within these areas, an additional two-years of field collections and data processing was added to a 12-year WNV dataset that includes human cases, MIR, vector abundance, and land-use, historical climate, and socio-economic and demographic variables, and was assessed by an ultra-fine-scale (1 km spatial x 1 week temporal resolution) multivariate logistic regression model.ResultsMultivariate statistical methods applied to the ultra-fine-scale model identified fewer explanatory variables while improving upon the fit of the previous model. Beyond MIR and climatic factors, efforts to acquire additional covariates only slightly improved model predictive performance.ConclusionsThese results suggest human WNV illness in the Chicago area may be associated with fewer, but increasingly critical, key variables at finer scales. Given limited resources, these findings suggest large variations in model performance occur, depending on covariate availability, and provide guidance in variable selection for optimal WNV human illness modeling.

Epidemiology and Outcomes of Vancomycin-Resistant Enterococcus Infections in the U.S. Military Health System.

Vancomycin-resistant enterococci (VRE) are classified by the Centers for Diseases Control and Prevention as a serious antibiotic resistance threat. Our study aims to characterize the epidemiology, associated conditions, and outcomes of VRE infections among hospitalized patients in the U.S. military health system (MHS). We performed a retrospective cohort study of patients with VRE infection using the MHS database. Cases included all patients admitted to a military treatment facility for ≥2 days from October 2008 to September 2015 with a clinical culture growing Enterococcus faecalis, Enterococcus faecium, or Enterococcus species (unspecified), reported as resistant to vancomycin. Co-morbid conditions and procedures associated with VRE infection were identified by multivariable conditional logistic regression. Patient case-mix adjusted outcomes including in-hospital mortality, length of stay, and hospitalization cost were evaluated by high-dimensional propensity score adjustment. During the seven-year study period and among 1,161,335 hospitalized patients within the MHS, we identified 577 (0.05%) patients with VRE infection. A majority of VRE infections were urinary tract infections (57.7%), followed by bloodstream (24.7%), other site/device-related (12.9%), respiratory (2.9%), and wound infections (1.8%). Risk factors for VRE infection included invasive gastrointestinal, pulmonary, and urologic procedures, indwelling devices, and exposure to 4th generation cephalosporins, but not to glycopeptides. Patients hospitalized with VRE infection had significantly higher hospitalization costs (attributable difference [AD] $135,534, P<0.001), prolonged hospital stays (AD 20.44 days, P<0.001, and higher in-hospital mortality (case-mix adjusted odds ratio 5.77; 95% confidence interval 4.59-7.25). VRE infections carry a considerable burden for hospitalized patients given their impact on length of stay, hospitalization costs, and in-hospital mortality. Active surveillance and infection control efforts should target those identified as high-risk for VRE infection. Antimicrobial stewardship programs should focus on limiting exposure to 4th generation cephalosporins.

Learning Models for Seismic-Induced Vibrations Optimal Control in Structures via Random Forests

Data-driven modeling of dynamical systems gathers attention in several applications; in conjunction with model predictive control, novel different identification techniques that merge machine learning and optimization are presented and compared with the purpose of reducing seismic response of frame structures and minimize control effort. Performance of neural network-, random forest- and regression tree-based identification algorithms in producing reliable models exploiting historical data coming from a real structure is shown. Peculiarities of each data-driven-based model emphasizing the strong potentialities of such approaches are highlighted, and it is shown in a simulative environment how, by slightly increasing the complexity of a model via random forests, we can reduce by half the active control effort with respect to the control computed exploiting regression trees-based models.

Output-Constrained Robust Sliding Mode Based Nonlinear Active Suspension Control

The nonlinear active suspension control design can be analyzed as a multiobjective control problem that caters to the enhancement in ride comfort levels while ensuring that road holding is maintained with the constrained suspension displacement movement. In this article, a robust constrained output feedback approach employing sliding mode controllers is proposed for the nonlinear active suspension system equipped with hydraulic actuators. Adhering to mechanical design limitations, the suspension displacement and the corresponding displacement rate are constrained using asymmetric barrier Lyapunov functions. Consequently, a nonlinear control law that incorporates the first-order sliding mode control is then formulated to regulate the hydraulic valve and thereby provide an active control effort. The robust control performance with high-performance improvements for ride comfort in the presence of parametric uncertainties, sensor noise, and over variable driving velocities for different road conditions is established using simulation studies.

Epidemiology, Associated Conditions, and Outcomes of Hospital Associated Vancomycin-Resistant Enterococcus Infections in the US Military Health Care System

BackgroundBetter strategies to combat vancomycin-resistant Enterococcus (VRE) infections are needed. Our study aims to characterize the epidemiology and associated conditions, and to measure the attributable cost, length of stay, and in-hospital mortality of VRE infections among hospitalized patients in the US military health system (MHS).MethodsWe performed a retrospective cohort study of patients with VRE infections using MHS database billing records. Cases included all patients admitted to a military treatment facility for ≥2 days from October 2008 to September 2015 with a clinical culture growing Enterococcus faecalis, Enterococcus faecium or Enterococcus species (unidentified), reported as resistant to vancomycin. Comorbid conditions and procedures associated with VRE infection were identified by multivariable logistic regression. Patient case-mix adjusted outcomes including in-hospital mortality, length of stay, and hospitalization cost were evaluated by high-dimensional propensity score adjusted logistic regression.ResultsDuring the 7-year study period and among 1,161,335 hospitalized patients within the MHS, we identified 577 (0.050%) patients with VRE infection. A majority of VRE infections were urinary tract infections (57.7%), followed by bloodstream (24.7%), other site/device-related (12.9%), respiratory (2.9%), and wound infections (1.8%). Risk factors for VRE infection included invasive gastrointestinal and urologic procedures, tracheostomy, as well as recent exposure to glycopeptides and extended-spectrum penicillins. Patients hospitalized with VRE infection had significantly higher hospitalization cost (attributable difference [AD] $117,322, P < 0.001), prolonged hospital stay (AD 20.45 days, P < 0.001, and in-hospital mortality (case-mix adjusted odds ratio 5.77; 95% confidence interval 4.59–7.25).ConclusionVRE infection in hospitalized patients is associated with an increased length of stay, hospital cost, and in-hospital mortality. Active surveillance and infection control efforts should target those identified as high-risk for VRE infection. Antimicrobial stewardship programs should focus on limiting exposure to vancomycin and extended-spectrum penicillins.Disclosures All authors: No reported disclosures.

Algorithm design of an hybrid system embedding influence of soil for dynamic vibration control

The paper outlines an approach for improving the effectiveness and reliability of base isolation devices in civil engineering structures that undergo exceptional dynamic conditions.The strategy consists of designing the passive device in such a way to take into account the not-negligible soil–structure interaction effects. At this stage, the isolator is, then, designed in such a way to be optimally tuned on the basis of the characteristics of the structure and of the soil at the site. Anyway limits intrinsic in the effectiveness of the passive device cannot be completely overcome even when embedding in the design the influence of the soil filtering on the structural response. Therefore, at the second stage, an active vibration device is coupled to the basic isolator, which is, in turn, optimally designed for minimizing the structural response and control costs. The overall presented approach definitively produces an effective hybrid control base isolation, already optimized for the specific structure and soil in its passive component, and able to concentrate the active control effort only on the frequency ranges where it is required.

Nonlinear Trajectory Tracking Control for Heavy-Haul Trains

In this paper, a nonlinear control is proposed for trajectory tracking of heavy-haul trains. The distinctive feature of the proposed control strategy is that, no active control efforts are exerted on wagons; and braking forces of wagons are considered as resistance, such that constraints of negative values on controls for wagons are avoided. It is proved that, the wagons can be regarded as the internal dynamics of the full-state system, and states of wagons are ultimately bounded. The control strategy for locomotives is designed based on nonlinear consensus of networked systems. Theoretical proof indicates that, with the proposed control, tracking errors of the closed-loop system are globally asymptotically stable. Simulation results are displayed to illustrate the performances of the closed-loop system.

Indigenous women and smoking during pregnancy: Knowledge, cultural contexts and barriers to cessation

Despite active tobacco control efforts in Australia, smoking prevalence remains disproportionately high in pregnant Indigenous women. This study investigated the place of smoking in pregnancy and attitudes towards smoking within the broader context of Indigenous lives. Focus groups and in-depth interviews were used to collect data from 40 women, and ten Aboriginal Health Workers (AHWs) in Perth, Western Australia. The research process and interpretation was assisted by working with an Indigenous community reference group. Results demonstrated the impact of contextual factors in smoking maintenance, and showed that smoking cessation even in pregnancy was not a priority for most women, given the considerable social and economic pressures that they face in their lives. Overwhelmingly, smoking was believed to reduce stress and to provide opportunities for relaxation. Pregnancy did not necessarily influence attitudes to cessation, though women's understanding of the consequences of smoking during pregnancy was low. Reduction of cigarette intake during pregnancy was seen as an acceptable and positive behaviour change. The AHWs saw their role to be primarily one of support and were conscious of the importance of maintaining positive relationships. As a result, they were often uncomfortable with raising the issue of smoking cessation with pregnant women. The stories of Indigenous women and AHWs provided important insight into smoking during pregnancy and the context in which it occurs.

Modelling the potential spread of Solenopsis invicta Buren (Hymenoptera: Formicidae) (red imported fire ant) in Australia

Quantifying the potential spread and density of an invading organism enables decision-makers to determine the most appropriate response to incursions. We present two linked models that estimate the spread of Solenopsis invicta Buren (red imported fire ant) in Australia based on limited data gathered after its discovery in Brisbane in 2001. A stochastic cellular automaton determines spread within a location (100 km by 100 km) and this is coupled with a model that simulates human-mediated movement of S. invicta to new locations. In the absence of any control measures, the models predict that S. invicta could cover 763 000–4 066 000 km2 by the year 2035 and be found at 200 separate locations around Australia by 2017–2027, depending on the rate of spread. These estimated rates of expansion (assuming no control efforts were in place) are higher than those experienced in the USA in the 1940s during the early invasion phases in that country. Active control efforts and quarantine controls in the USA (including a concerted eradication attempt in the 1960s) may have slowed spread. Further, milder winters, the presence of the polygynous social form, increased trade and human mobility in Australia in 2000s compared with the USA in 1940s could contribute to faster range expansion.

Active control effort of hybrid piezoelectric absorber for structural control

This paper aims at addressing the active control effort of the active-shunted hybrid piezoelectric absorber for structural vibration suppression. Both active control efforts of the integrated and separated hybrid piezoelectric absorbers are analyzed by using a simple cantilevered beam example. It is recognized that a new hybrid piezoelectric absorber based on a switching operation is capable of reducing the active control effort. A switching type of the hybrid piezoelectric absorber can be developed by the simple combination of integrated and separated hybrid piezoelectric absorbers. It is demonstrated that the switching type of the absorber has the capability of the trade-off between the active control effort and the damping performance.

Eye disease in multibacillary leprosy patients at the time of their leprosy diagnosis: findings from the Longitudinal Study of Ocular Leprosy (LOSOL) in India, the Philippines and Ethiopia

Existing prevalence surveys do not provide adequate information to estimate the magnitude of ocular pathology or vision loss in leprosy patients. We sought to determine the prevalence of ocular findings and related risk factors in leprosy patients at the time of their disease diagnosis. We also sought to determine if there were geographic differences and whether these were due to different demographic characteristics of the populations. The study was undertaken at Schieffelin Leprosy Research & Training Centre (Karigiri, India), Leonard Wood Memorial Leprosy Institute (Cebu, Philippines), and (for 3 years only) ALERT (Addis Ababa, Ethiopia). Newly diagnosed multibacillary (MB) leprosy patients as well as MB cases relapsed after dapsone monotherapy were eligible for enrollment. In each study site, the target population was 300. Standardized examinations were conducted between 1991 and 1998. Patient enrollment included 301 patients in Karigiri, 289 patients in Cebu, and 101 patients in Addis Ababa. The age-adjusted prevalence of blindness (< 6/60 in the better eye) and visual impairment (6/24-6/60) was 2.8% and 5.2%, respectively. Lagophthalmos and leprosy related uveal changes were detected in 3.3% (95% CI 2.0-4.7%) and 4.1% (95% CI 2.4-5.7) of patients, respectively. Overall, 11% (95% CI 8.5-13.2%) of newly enrolled MB patients had potentially blinding leprosy related ocular pathology. Lagophthalmos was associated with increasing age, a short duration between onset and diagnosis, and a previous reaction involving the face. Uveal conditions were associated with increasing age. Overall, eye disease was more common in Indian and Ethiopian patients compared to Filipino patients; however, differences were not significant when controlling for age and clinical (non-ocular) factors. Patients with potentially blinding leprosy related pathology were over three times more likely to have other (hand and foot) disabilities than patients without pathology. Differences in the prevalence of blindness and potentially blinding leprosy related ocular pathology between the sites could be accounted for by the differences in age and other clinical factors of the patients at the different sites. Findings suggest that, even in the face of active leprosy control efforts, around 11% of patients will have potentially blinding pathology at the time of their diagnosis and 2.8% will be blind. If those patients with lagophthalmos or blindness are considered appropriate for referral for more detailed assessment, approximately 4% of newly diagnosed leprosy patients will require active follow-up for eye care; including those with reaction involving the face will result in 9.4% of patients requiring active follow-up. These people are likely to be older, with a reaction involving the face, and/or with other disabilities than those not requiring active follow-up.

Optimal Redesign of Linear Systems

This paper proposes a redesign procedure for linear systems. We suppose that an initial satisfactory controller which yields the desired performance is given. Then both the plant and the controller are redesigned to minimize the required active control effort. Either the closed-loop system matrix or the closed-loop covariance matrix of the initial design can be preserved under the redesign. Convex quadratic programming solves this problem. In addition, an iterative approach for integrated plant and controller design is proposed, which uses the above optimal plant/controller redesign in each iterative step. The algorithm has guaranteed convergence and provides a sequence of designs with monotonically decreasing active control effort. Examples are included to illustrate the procedure.

Optimum design of space structures with active and passive damping

This paper investigates the effects of passive damping on the optimum structural design with active controllers. An integrated design of structure and active control system is performed. The minimum weight design is obtained by imposing constraints on the closed-loop damping and the imaginary part of the closed-loop eigenvalues of the active control system. The mathematical optimization problem is solved by using the NEWSUMT-A program, which is based on quadratic extended interior penalty function method. The ACOSS-FOUR model is selected for the numerical studies. The active control effort, performance index, and optimum weights are presented as a function of the passive damping.