Trajectory Generation for Stair Ascent Walking using Rayleigh Oscillator

This paper describes a trajectory generation technique for stair-ascent walking. The knee, hip and ankle joint trajectory during stair ascent are generated using mutually coupled, nonlinear oscillators. The parameters of the oscillators are tuned using the harmonic balance method, which converts the nonlinear differential equations to a set of algebraic equations. Fourier analysis of data generated by stair-ascent walking is performed to extract the amplitude and the phase of the dominant frequency components for each joint trajectory. The solution for the oscillator is assumed to be a sinusoidal wave and then by harmonic balance method the parameters of the oscillator are found. Each oscillator is responsible for generating a single frequency component with a specific phase and amplitude. The complete trajectory is obtained by summing the output of the oscillators that are relevant to one joint and the coupling maintains the phase relationship between the oscillators

Pretreatment of Miscanthus giganteus with Lime and Oxidants for Biofuels

ACKNOWLEDEGMENTS The authors are grateful to the Energy Biosciences Institute, University of California, Berkeley, Berkeley, CA, for financial support, Dr. Stefan R. Bauer, Valerie D. Mitchell, and Ana Belen Ibanez Zamora for technical assistance, and Jason Cai for fruitful discussions. The authors thank the China Scholarship Council for financial assistance to Fuxin Yang during his stay at University of California, Berkeley.Peer reviewedPostprin

Wound healing suppressant effect of vincristine reversed by vitamin A: an experimental study

Background: Use of antineoplastic drugs pre and postoperatively have shown to adversely affect the healing of surgical wounds. Vincristine is an antineoplastic drug with a wide range of antitumor activity. Prior studies have demonstrated that vincristine impairs skin wound healing.Methods: In this study we investigated the effect of vitamin A on vincristine induced suppression of healing in two wound models, viz: incision and dead space in rats. Hydroxyproline (measure of collagen) was estimated colorimetrically and breaking strength of the wound and granulation tissue was measured.Results: Vincristine (60 mcg/Kg intraperitoneally, on the 3rd wounding day) significantly reduced breaking strength in both incision and dead space wound models. Vitamin A (5000 I.U, Subcutaneously on alternate days) by itself did not alter any of the parameters studied but reversed the suppressant effects of vincristine on wound healing.Conclusions: Vitamin A by itself produced little effect on healing except a modest increase in granulation mass. But it significantly reversed the healing suppressant effects of vincristine

Effect of Particle Size on Mechanical Properties of Pellets Made from Biomass Blends

AbstractWoody biomass is densified in the form of pellets in order to improve its physical and mechanical properties during handling and storage. However, limited research work has been conducted on the mechanical properties of pellets made from agricultural and wood biomass blends. Two commonly available forestry biomass, spruce (S) and pine (P), and three agricultural biomasses, reed canary grass (RCG), timothy hay (H) and switchgrass (SW), were used to form pellets. The mechanical properties were evaluated for three different particle sizes (150-300, 300-425 and 425-600μm). An Instron attached with an in-house built single unit pelletizer and temperature controlled die was employed to produce a pellet. The aim of this study is to investigate the effect of particle size and blending (agricultural and woody biomass) on the mechanical properties (density and intrinsic yield stress). For all biomasses, pellets made from lower particle size (150-300μm) exhibited higher density (950-1178kg/m3 for spruce and pine; 668-800kg/m3 for RCG, H and SW; 900-970kg/m3 for blended biomass). The intrinsic yield stress exhibited differences in values for individual forestry (40MPa) and agricultural biomass (27-48MPa), however after blending the values converged closest to that value for forestry biomass. In conclusion, blending low cost and abundant available agricultural biomass with woody biomass could not only result in better mechanical properties but would also help to meet the pellet market demand in future

Assessment of Moisture Effect in Simulating Forestry Biomass Supply Chain Strategy: Case Study of New Brunswick, Canada

In order to investigate the effect of variation of the moisture content of forest biomass residues on a supply chain strategy, a simulation was performed using integrated biomass supply analysis and logistics modeling. A simple supply chain strategy was chosen and applied for Miramichi and Plaster Rock, two different regions in New Brunswick, Canada. These regions are selected based on three criteria: annual potential harvest of forest biomass residues, annual production potential of electric and thermal energy and distribution of transportation zones. The moisture content of forest biomass residues was dependant on the weather conditions of the selected regions. The results show that the moisture content of the biomass in Plaster Rock was more stable but higher than the biomass in the Miramichi region. In simulating the supply chain strategy, particular attention is given to harvest, baling, storage and transportation of the biomass. The simulation results show that, during harvest and baling of the biomass, the moisture content affects the dry matter loss and, as a consequence, the customer and ownership costs of the operations. It also affects the energy input and the quantity of carbon dioxide released in the atmosphere. However, dry matter loss and accordingly the cost of the operations are the main parameters affecting the storage and transportation of forest biomass residues

Nanoindentation characterization of microwave-pyrolysis biochar

This study investigates the nanoindentation hardness and Young’s modulus of microwave pyrolysis biochar developed from hemp and softwood feedstocks. Recent studies have produced encouraging results on the potential for biochar as a reinforcing filler in composite materials, owing to the high porosity and hardness of the carbonous material. In order to further the understanding of the effect of biochar as an additive, and to develop predictive models for the composites, mechanical properties of the chars are needed. The biochar was synthesized from both hemp and softwood feedstocks, in-house through a microwave-pyrolysis process at 2700 watts, for one hour, with heating rates reaching 50 °C/min and residence temperatures of up to 660°C. Proximate and ultimate analysis were performed as well as physiosorption analysis in order to relate the nanoindentation results to the biochar characteristics. Proximate analysis indicated larger fixed carbon content of softwood (71 wt%), and hemp (72 wt%) with inverse trend for volatile matter. Biochar samples of both softwood and hemp showed an H:C ratio of 2/g BET surface area and 2.58 m2/g micropore area, compared to 9.96 m2/g and 1.63 m2/g BET surface area and micropore area of softwood. Prior to nanoindentation, biochar samples from each feedstock were cold-mounted, then polished with decreasing grit sizes from 500 to 1200 microns. The Young’s modulus and hardness values of the biochar samples were obtained from an iMicro Nanoindentor using a 1mN load. An average of ten indentations were performed on the mounted biochar samples. Nanoindentation results indicated Young’s modulus of 5.98 and 5.64 GPa as well as hardness of 0.26 and 0.51 GPa for hemp and softwood char respectively. Considering the nanoindentation results it was observed that heating rates/residence temperatures of pyrolysis and porosity of the biochar are the main factors in overall hardness and modulus. High pyrolysis temperatures allow the char to carbonize to a hardened glass-like state, while faster heating rates aid in the release of softer pyrolytic tars and residue. Furthermore the higher development of healthy micropores at faster heating rates leads to a stronger porous structure, increasing the Young’s modulus. Overall the findings from this study are important indicators of the factors influencing the potential of biochar as a reinforcing filler in biocomposite materials. Knowing the Young’s modulus and hardness of biochar is highly useful in the development of analytical predictive models describing the behavior of biochar reinforced biocomposites under various loading conditions

Adsorption of Pb2+ on magnetic modified hemp biochar prepared using microwave-assisted pyrolysis

Magnetic modified hemp biochar with an aim of high adsorption capacity and rapid adsorption rate was prepared by two simple steps using microwave pyrolyzed biochar. This was investigated as a potential green adsorbent for lead remediation from wastewater in a batch-mode experiment. The 150 – 300 µm biochar particles obtained from microwave-assisted pyrolysis of 1.5 kg hemp biomass batch at an average temperature of 600˚C were first impregnated with H2O2 and then magnetized by mixing aqueous biochar suspensions with aqueous Fe3+/Fe2+ solutions. The composition, morphology and surface chemistries of this magnetic biochar was examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM) and BET surface area (SBET). The SBET of the magnetic hemp biochar is 83.76 m2 g-1. Batch sorption studies were performed for a 50 mg L-1 lead solution at room temperature and pH 5.5 using 0.02 g of the magnetic adsorbent in 20 ml solution for 2 hours. The experimental results have shown that the adsorption capacity of this magnetic adsorbent for Pb2+ is 43.97 mg g-1, about 87.94% removal within the 2 hours. Both pseudo-second-order and pseudo-first-order kinetic model could predict the adsorption and desorption kinetic process on the modified sorbent. EDX analysis are used to show the mechanisms for the adsorption of Pb2+ onto the adsorbent via mainly ion exchange. The Freundlich, Temkin and Langmuir models are used to predict the sorption isotherm in the system. The as-prepared magnetic hemp sorbent demonstrated a potential in heavy metal wastewater treatment

Additively Manufactured Perforated Superstrate to Improve Directive Radiation Characteristics of Electromagnetic Source

© 2013 IEEE. Additively manufactured perforated superstrate (AMPS) is presented to realize directive radio frequency (RF) front-end antennas. The superstrate comprises spatially distributed dielectric unit-cell elements with square perforations, which creates a pre-defined transmission phase delay pattern in the propagating electric field. The proposed square perforation has superior transmission phase characteristics compared to traditionally machined circular perforations and full-wave simulations based parametric analysis has been performed to highlight this supremacy. The AMPS is used with a classical electromagnetic-bandgap resonator antenna (ERA) to improve its directive radiation characteristics. A prototype is developed using the most common, low-cost and easily accessible Acrylonitrile Butadiene Styrene (ABS) filament. The prototype was rapidly fabricated in less than five hours and weighs 139.3 g., which corresponds to the material cost of only 2.1 USD. The AMPS has remarkably improved the radiation performance of ERA by increasing its far-field directivity from 12.67 dB to 21.12 dB and reducing side-lobe level from-7.3 dB to-17.2 dB

Psychotropic Agents Poisoning: Analysis of Cases Reported to Shahid Beheshti Drug and Poison Information Center

Background: Antidepressants, antipsychotics and benzodiazepines overdose events are the most reported poisoning each year from Shahid Beheshti Drug and Poison Information Center (DPIC) (a branch of Iran Drug and Poison Information Center in Tehran), which clearly shows the necessity of providing prevention program and instruction plan in taking psychotropic agents.Methods: This survey was a descriptive retrospective study by reviewing 390 reported phone calls from Shahid Beheshti Drug and Poison Information Center (DPIC), in Tehran, through 2010 to 2012.Results: 390 reported cases of psychotropic agents including overdoses, medical errors such as extra dose, accidental exposure of medications, especially in children, cases of suicide, and intentional use (were) recorded. The main causes of poisoning calls to the DPIC, were included intentional and suicidal actions (40%), accidental events (27%), drug abuse (26%) and, medical errors (7%), respectively. Up to 50% of calls were about benzodiazepines (BZD) poisoning and the most adverse effects were Central Nervous System (CNS) effects followed by gastrointestinal side effects.Conclusion: According to the results, in order to achieve the proper effect of psychotropic agents and preventing related poisoning, providing pharmaceutical services and awareness of patients are necessary. It should be about the therapeutic effects and side effects of their medications by pharmacists and poison centers and limiting the accessibility of patients to large amounts of these medications by regulatory organizations

Exposure to NO2 in occupational built environments in urban centre in Lahore

Increased economic growth, urbanisation and substantial rise in automobile vehicles has contributed towards the elevated levels of air pollution in major cities in Pakistan. Aone week study was conducted by using passive samplers to assess NO2 concentration in occupational built environments at two most congested and populated sites of Lahore. Both sites were locatedon the busy roads of Lahore. At Site-I the highest concentration was in outdoors followed by corridor and indoor. While at Site II all the sampling location wereindoors and level were comparable to that of outdoor levelsat Site I. The results suggest the likely contribution of ambient sources in exposure to indoor NO2 in educational and other occupational built environments in urban centres