A variational approach to path planning for hyper-redundant manipulators

Motion planning for hyper-redundant manipulators in a complicated and cluttered workspace is a challenging problem. Many of the path planning algorithms, based on cell decomposition or potential field, fail due to the high dimensionality and complex nature of the C-space. Probabilistic roadmap methods (PRM) which have been proven to be successful in high dimensional C-spaces suffer from the drawback of generating paths which involve a lot of redundant motion. In this paper, we propose a path optimizing method to improve a given path in terms of path length and the safety against the collisions, using a variational approach. The capability of variational calculus to optimize a path is demonstrated on a variety of examples. The approach succeeds in providing a good quality path even in high dimensional C-spaces.     

Sorption Isotherms and Drying Characteristics of Tomato Peel Isolated from Tomato Pomace

Tomato peel was separated from pomace by sedimentation and dried in cabinet and fluidized-bed dryer at 50–70°C using 4–12 kg/m²tray load. The drying of tomato peel took place under the falling rate period and the drying behavior was well described by Page's model with coefficient of determination greater than 0.99 and standard error of 0.003–0.016. A fluidized-bed dryer was much more efficient than a cabinet dryer to dry tomato peel. The moisture adsorption isotherms of tomato peel were obtained by equilibrating above saturated salt solutions of known a _w (0.113–0.92) at 20–60°C. The data were analyzed using fifteen sorption models based on coefficient of determination, standard error, and residual plots. Modified Henderson was the best model for tomato peel with coefficient of determination >0.99, standard error <0.210, and a scattered residual plot. The net isostearic heat of sorption, estimated using the Clausius-Clapeyron equation, was 0.74–23.23 kJ/mol at 2.0–2.5% moisture content (dry basis).     

Analytical modeling of subthreshold current and subthreshold swing of Gaussiandoped strained-Si-on-insulator MOSFETs

This paper presents the analytical modeling of subthreshold current and subthreshold swing of short- channel fully-depleted （FD） strained-Si-on-insulator （SSOI） MOSFETs having vertical Gaussian-like doping pro- file in the channel. The subthreshold current and subthreshold swing have been derived using the parabolic approx- imation method. In addition to the effect of strain on silicon layer, various other device parameters such as channel length （L）, gate-oxide thickness （tox）, strained-Si channel thickness （ts_Si）, peak doping concentration （Np）, project range （Rp） and straggle （op） of the Gaussian profile have been considered while predicting the device characteris- tics. The present work may help to overcome the degradation in subthreshold characteristics with strain engineering. These subthreshold current and swing models provide valuable information for strained-Si MOSFET design. Ac- curacy of the proposed models is verified using the commercially available ATLASTM, a two-dimensional （2D） device simulator from SILVACO.     

Moisture Adsorption Isotherms of Watermelon Seed and Kernels

The moisture adsorption isotherms of watermelon seeds and kernels from Citrullus lanatus Cv Mateera and Citrullus vulgaris Cv Sugar baby were obtained using standard static method with saturated salt solutions over a range of water activities from 0.113 to 0.92 at 20-60°C. The adsorption capacity of seeds decreased with the increase in temperature at constant water activity. Sorption models were used to explain the adsorption behavior involving water activity and moisture content (Type I) and also temperature (Type II). Oswin's models gave best fit among Type I with coefficient of determination of 0.953-0.995, standard error of 0.031-0.0571, mean relative error of 0.071-0.152, and scattered residual plots. Modified Oswin was the best fit model among Type II for the seeds and kernels of both the cultivars with coefficient of determination of 0.997-0.999, standard error of 0.151-0.255, mean relative error of 0.018-0.244, and scattered residual plots. The net isoelectric heat of adsorption, estimated from Clausius-Clapeyron decreased from about 27.0 to 0.5 kJ/mol in kernels and 18.0 to 0.5 kJ/mol in seeds of both the cultivars as the moisture content increased from 5 to 25% (dry basis).     

Performance improvement of 60‐GHz wireless optical systems with reverse‐parallel hybrid modulation scheme

This paper improves the performance of 60‐GHz wireless optical system including radio over fibre (RoF) and radio over free space optics (RoFSO), based on novel reverse‐parallel (RP) hybrid modulation scheme. This scheme combines the chromatic dispersion compensation technique of parallel modulation with energy efficiency manipulation technique of reverse modulation. Superior functioning of RoFSO is provided with reverse modulation compared with normal modulation. Comparative investigations are performed by loading 60‐GHz RF signal with 2.5 and 10‐Gbps data and modulating it with both reverse and hybrid modulators. Hybrid modulation performed better with improved BER of 10^?23 at distance of 51 km for 2.5‐Gbps data compared with reverse modulation with BER of 10^?7.     

Genetically Programmed Regioselective Immobilization of Enzymes in Biosilica Microparticles

Diatoms are single‐celled microalgae that produce a large variety of hierarchically porous, silica‐based microparticles as cell wall material. The presence of genetically encoded silica nanopatterns endows the biosilica with favorable properties for a wide range of applications including catalysis, chemical sensing, photonics, and drug delivery. Enhancing the performance of diatom biosilica requires i) a better understanding of the structure–property relationship in this material, and ii) methods that enable the manipulation of the biosilica structure and properties in a targeted manner. Here, genetic engineering of the diatom Thalassiosira pseudonana is employed to immobilize enzymes (glucose oxidase and horseradish peroxidase) into structurally distinct regions of the biosilica, which are termed valves and girdle bands. Remarkably, glucose oxidase in girdle bands exhibits >3‐fold higher catalytic activities compared to its location in valves. It is demonstrated through enzyme accessibility studies, protein engineering, and genetic engineering of biosilica morphology that the divergent enzyme activities are caused by the differences in the inherent silica nanopatterns of valves and girdle bands. This work highlights the importance of silica nanoscale architecture for the activity of immobilized enzymes and provides unprecedented tools for the biotechnological production of silica microparticles with tailored catalytic activities and anisotropic functionalities.     

Probing peptide nanotube self-assembly at a liquid-liquid interface with coarse-grained molecular dynamics

Self-assembly at a liquid-liquid interface is a powerful experimental route to novel nanomaterials. We report herein a computational study of peptide nanotube formation at an oil-water interface. We probe interfacial self-assembly and nanotube formation of the cyclic octapeptide, cyclo [(-L-Trp-D-Leu-)4] as an illustrative example. Individual peptide rings are rapidly adsorbed at the liquid-liquid interface where they self-assemble. Monomeric and dimeric peptide rings lie with their molecular planes mostly parallel to the interface. Longer oligomeric nanotubes are increasingly tilted at the interface and grow by an Oswald ripening mechanism to eventually align their tube axis parallel to the interface. The present results on nanotube assembly suggest that computation will be a useful complement to experiment in understanding the nature of self-assembly of nanomaterials at liquid-liquid interfaces.