Robust loop shaping-fuzzy gain scheduling control of a servo-pneumatic system using particle swarm optimization approach

In this paper, a new technique called robust loop shaping-fuzzy gain scheduled control (RLS-FGS) is proposed to design an effective nonlinear controller for a long stroke pneumatic servo system. In our technique, a nonlinear dynamic model of a long stroke pneumatic servo plant is identified by the fuzzy identification method and is used as the plant for our design. The structure of local controllers is selected as PID control which is proven by many research works that this type of control has many advantages such as simple structure, well understanding, and high performance. The proposed technique uses particle swarm optimization (PSO) to find the optimal local controllers which maximize the average stability margin. In addition, performance weighting function which is normally difficult to obtain is automatically determined by PSO. By the proposed technique, the RLS-FGS controller can be designed, and the structure of local controllers is still not complicated. As seen in the simulation and experimental results, our proposed technique is better than the classical gain scheduled PID controller tuned by pole placement and the conventional fuzzy PID controller tuned by ISE method in terms of robust performance.     

Robust Finite-time <Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript> Control of Linear Time-varying Delay Systems with Bounded Control via Riccati Equations

In this paper, we will present new results on robust finite-time H_∞ control for linear time-varying systems with both time-varying delay and bounded control. Delay-dependent sufficient conditions for robust finite-time stabilization and H_∞ control are first established to guarantee finite-time stability of the closed-loop system via solving Riccati differential equations. Applications to finite-time H_∞ control to a class of linear autonomous time-delay systems with bounded control are also discussed in this paper. Numerical examples are given to illustrate the effectiveness of the proposed method.     

Simultaneous thermophilic hydrogen production and phenol removal from palm oil mill effluent by Thermoanaerobacterium-rich sludge

Thermoanaerobacterium-rich sludge was used for hydrogen production and phenol removal from palm oil mill effluent (POME) in the presence of phenol concentration of 100–1000 mg/L. Thermoanaerobacterium-rich sludge yielded the most hydrogen of 4.2 L H₂/L-POME with 65% phenol removal efficiency at 400 mg/L phenol. Butyric acid and acetic acid were the main metabolites. The effects of oil palm ash, NH₄NO₃ and iron concentration (Fe²⁺) on hydrogen production and phenol removal efficiency from POME by Thermoanaerobacterium-rich sludge was investigated using response surface methodology (RSM). The RSM results indicated that the presence of 0.2 g Fe²⁺/L, 0.3 g/L NH₄NO₃ and 20 g/L oil palm ash in POME could improved phenol removal efficiency, with predicted hydrogen production and phenol removal efficiency of 3.45 L H₂/L-POME and 93%, respectively. In a confirmation experiment under optimized conditions highly reproducible results were obtained, with hydrogen production and phenol removal efficiency of 3.43 ± 0.12 L H₂/L-POME and 92 ± 1.5%, respectively. Simultaneous hydrogen production and phenol removal efficiency in continuous stirred tank reactor at hydraulic retention time (HRT) of 1 and 2 days were 4.0 L H₂/L-POME with 85% and 4.2 L H₂/L-POME with 92%, respectively. Phenol degrading Thermoanaerobacterium-rich sludge comprised of Thermoanaerobacterium thermosaccharolyticum, Thermoanaerobacterium aciditolerans, Desulfotomaculum sp., Bacillus coagulans and Clostridium uzonii. Phenol degrading Thermoanaerobacterium-rich sludge has great potential to harvest hydrogen from phenol-containing wastewater.     

Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells

Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.     

analysis of pedestrian accident costs in Sudan using the willingness-to-pay method

The willingness-to-pay (WTP) with contingent valuation (CV) method has been proven to be a valid tool for the valuation of non-market goods or socio-economic costs of road traffic accidents among communities in developed and developing countries. Research on accident costing tends to estimate the value of statistical life (VOSL) for all road users by providing a principle for the evaluation of road safety interventions in cost-benefit analysis. As in many other developing countries, the economic loss of traffic accidents in Sudan is noticeable; however, analytical research to estimate the magnitude and impact of that loss is lacking. Reports have shown that pedestrians account for more than 40% of the total number of fatalities. In this study, the WTP-CV approach was used to determine the amount of money that pedestrians in Sudan are willing to pay to reduce the risk of their own death. The impact of the socioeconomic factors, risk levels, and walking behaviors of pedestrians on their WTP for fatality risk reduction was also evaluated. Data were collected from two cities—Khartoum and Nyala—using a survey questionnaire that included 1400 respondents. The WTP-CV Payment Card Questionnaire was designed to ensure that Sudan pedestrians can easily determine the amount of money that would be required to reduce the fatality risk from a pedestrian-related accident. The analysis results show that the estimated VOSL for Sudanese pedestrians ranges from US$0.019 to US$0.101 million. In addition, the willingness-to-pay by Sudanese pedestrians to reduce their fatality risk tends to increase with age, household income, educational level, safety perception, and average time spent on social activities with family and community.     

Highway infrastructure and state-level employment: A causal spatial analysis

This paper analyses the causal relationship between highway infrastructure and employment within the U.S. We estimate dynamic panel models in a vector autoregressive framework using time-series cross-sectional data on lane miles of roadway capacity and private sector employment for the 48 contiguous states over the period 1984–1997. The issue of spatial dependence is explicitly taken into account by means of a spatial filtering technique. Our analysis reveals evidence of employment growth temporally influenced by annual growth in the provision of major highways within the same state and all other states, as well as the other way around. However, the results show that the existence and direction of these temporal and spatial effects depend on the type of highways and time lags considered.

Resumen

país comercial este artículo analiza la relación causal entre la infraestructura de autopistas y el empleo en los EE.UU. Estimamos modelos dinámico de datos de panel dentro de un marco autorregresivo vectorial utilizando datos transversales de series temporales en de capacidad de carretera en millas de carril y de empleo del sector privado para los 48 estados contiguos durante el periodo 1984–1997. Nuestro análisis revela pruebas de crecimiento del empleo influido temporalmente por el crecimiento anual en la provisión de autopistas principales dentro del mismo estado y el resto de estados, y a la inversa. Sin embargo, los resultados muestran que la existencia y dirección de estos efectos temporales y espaciales dependen del tipo de autopistas y los lapsos de tiempo considerados.