Fixed gain and adaptive techniques for rotorcraft vibration control

The results of an analysis effort performed to demonstrate the feasibility of employing approximate dynamical models and frequency shaped cost functional control law desgin techniques for helicopter vibration suppression are presented. Both fixed gain and adaptive control designs based on linear second order dynamical models were implemented in a detailed Rotor Systems Research Aircraft (RSRA) simulation to validate these active vibration suppression control laws. Approximate models of fuselage flexibility were included in the RSRA simulation in order to more accurately characterize the structural dynamics. The results for both the fixed gain and adaptive approaches are promising and provide a foundation for pursuing further validation in more extensive simulation studies and in wind tunnel and/or flight tests

Nutrient concentration of forage sorghum (Sorghum bicolor L) varieties under influenced of salinity and irrigation frequency.

The responses of forage sorghum [Sorghum bicolor (L.)Moench] varieties to salinity and irrigation frequency were studied from December 2008 to December 2009 at Universiti Putra Malaysia. Two salt tolerant varieties of forage sorghum, namely Speedfeed and KFS4, were grown under salinity levels of 0, 5, 10, 15 dS m-1 and irrigated when the leaf water potential reached -1(control),-1.5 and -2 MPa. Salinity and irrigation frequency significantly (P≤0.01) affected nutrient concentration of forage sorghum varieties tested. The factorial treatment combinations were arranged in a randomized complete block design with three replications.Sodium content decreased 7 and 17% among the irrigation frequency treatments of -1.5 and -2 MPa, respectively. Abrupt increases in Na contents were noticed at 5 and 10 dS m-1 salinity when Na accumulation increased 4 to 9 fold. Potassium diminished 29, 38 and 54% under 5, 10 and 15 dS m-1 salinity treatment respectively, and decreased 4 and 10% with increase in water stress to -1.5 and -2 MPa respectively. Accumulation of K+, Ca2+ and Mg+ in the shoots was strongly inhibited by salinity.Salinity substantially reduced plant growth as reflected by a decrease in the dry forage yields, and percent of mortality at high salinity levels. The maximum dry forage yields were 45.1, 38.9, and 38.5 g plant–1 for frequent, intermediate, and infrequent irrigation regimes, respectively. Based on salinity, the forage dry weight in control plants had the highest yield (44.09 g plant–1), while plants under the high salinity treatment gave the lowest yield (32.76 g plant–1)

Growth analysis of forage sorghum (Sorghum bicolor L) varieties under varying salinity and irrigation frequency.

Growth of forage sorghum [Sorghum bicolor (L.) Moench] varieties was assessed under saline conditions (EC 0, 5, 10, 15 dS m-1) and irrigated when the leaf water potential reached -1(control),-1.5 and -2 MPa. The forage sorghum varieties namely Speedfeed and KFS4 were differed significantly for emergence, leaf area index, relative growth rate and net assimilation rate. Plants grown under water stress and saline conditions resulted in decreased leaf area which subsequently led to reduced plant growth. Infrequently watered sorghum plants had reduced dry mater, LAI, NAR and eventually dry matter yield. These reductions were higher when lower irrigation frequency was coupled with salinity. The highly significant declined was mostly at -2 MPa irrigation frequency. This indicates that irrigation at 2 weeks interval or till leaf water potential reaches to -1.5 MPa, is possible for forage sorghum

Attracted Diffusion-Limited Aggregation

In this paper, we present results of extensive Monte Carlo simulations of diffusion-limited aggregation (DLA) with a seed placed on an attractive plane as a simple model in connection with the electrical double layers. We compute the fractal dimension of the aggregated patterns as a function of the attraction strength \alpha. For the patterns grown in both two and three dimensions, the fractal dimension shows a significant dependence on the attraction strength for small values of \alpha, and approaches to that of the ordinary two-dimensional (2D) DLA in the limit of large \alpha. For non-attracting case with \alpha=1, our results in three dimensions reproduce the patterns of 3D ordinary DLA, while in two dimensions our model leads to formation of a compact cluster with dimension two. For intermediate \alpha, the 3D clusters have quasi-2D structure with a fractal dimension very close to that of the ordinary 2D-DLA. This allows one to control morphology of a growing cluster by tuning a single external parameter \alpha.Comment: 6 pages, 6 figures, to appear in Phys. Rev. E (2012

Salinity effects on germination of forage sorghumes

Abstract: To investigate the effects of osmotic stress on forage sorghum (Sorghum bicolor L. Moench) varieties at critical stage of seed germination, i.e., at which salinization is initiated. A study was conducted at the Seed Technology Laboratory at University of Putra Malaysia (UPM- lab.) from October to November 2007. Two forage sorghum varieties (Speedfeed and KFS4) were evaluated in the salinity levels of 0, 5, 10, 15 dS m-1. The experimental design was Completely Random Design (CRD), which was based on factorial with 3 replications. In the experiment, seeds were germinated in covered, sterilized, disposable Petri dishes. Three parameters, namely germination percentage, germination rate, germination index and coefficient velocity of germination were estimated. The results of this study showed that different levels of salinity had significantly affected the germination percentage, germination rate germination index. In addition, a significant difference (1%) was also found in the germination percentage between the two varieties. Meanwhile, the mean comparison of the treatments showed that the germination percentage in distilled water (S1) was the highest (92.5%) and salinity dS m-1 (S4) had the lowest germination percentage. The maximum germination rate (35.58) and germination index (391.67) were retrieved from EC 0 and with the increasing salinity, these parameters were decreased. The evaluation of the two varieties showed that KFS4 (V1) had a higher germination percentage (82.91%) than the speed feed (72.5%). Consequently, the seed germination of KFS4 was better than the speed feed (in salty water and non-stress conditions). In other words, salt stress had been found to delay germination of both varieties

Microencapsulation of Bacillus velezensis Using Alginate-Gum Polymers Enriched with TiO2 and SiO2 Nanoparticles

Bacillus bacteria are a group of plant growth stimulants that increase plant growth and resistance to plant pathogens by producing various metabolites. With their large surface area and small size, nanoparticles can be used in controlled-release formulations and increase the efficiency of the desired product. Encapsulation of biological agents in combination with nanoparticles can be an essential step in increasing the performance of these agents in adverse environmental conditions. In this study, which is the result of a collaboration between scientists from Italy and Iran, Bacillus velezensis was encapsulated in alginate combined with whey protein and zedo, mastic, and tragacanth gums in the presence of silica and titania nanoparticles to obtain two-layer and multilayer assemblies acting as novel, smart micro-encapsulation systems. The results of laboratory studies showed that the B. velezensis could produce protease, lipase, siderophore, auxin, and a dissolution of mineral phosphate. Scanning electron microscopy images (SEM) showed that the studied microcapsules were almost spherical. Moisture affinity, swelling, and efficiency of each microcapsule were examined. The results showed that the highest encapsulation efficiency (94.3%) was related to the multilayer formulation of alginate-whey protein-zedo. XRD and FTIR spectroscopy showed that the alginate, whey protein, and zedo were mixed properly and no incompatible composition occurred in the reaction. This study aimed to provide a suitable formulation of biofertilizers based on biodegradable compounds as an alternative to chemical fertilizers, which is low cost and very effective without harming humans and the environment

Bringing social context into global biomedical HIV cure-related research: An urgent call to action

Advances in science have ushered in a wave of new potential curative and control strategies for HIV that could eliminate the current requirement for life-long antiretroviral therapy (ART) for people living with HIV (PLWH). In this article, we argue that it is critical to consider social contexts in the development of HIV cure trial protocols. The biological and behavioral risk factors for HIV acquisition by study participants are inseparable from the social context in which these participants live. The article discusses an example of a cohort established to further HIV cure research that included social context, called the FRESH Acute HIV study, which combines a sociostructural intervention while conducting HIV prevention, treatment and cure-related research in Durban, South Africa. We make an urgent call to action to include sociobehavioral components as instrumental in future HIV cure trials in global context

Bringing social context into global biomedical HIV cure-related research: An urgent call to action

Advances in science have ushered in a wave of new potential curative and control strategies for HIV that could eliminate the current requirement for life-long antiretroviral therapy (ART) for people living with HIV (PLWH). In this article, we argue that it is critical to consider social contexts in the development of HIV cure trial protocols. The biological and behavioral risk factors for HIV acquisition by study participants are inseparable from the social context in which these participants live. The article discusses an example of a cohort established to further HIV cure research that included social context, called the FRESH Acute HIV study, which combines a sociostructural intervention while conducting HIV prevention, treatment and cure-related research in Durban, South Africa. We make an urgent call to action to include sociobehavioral components as instrumental in future HIV cure trials in global context

Dietary intake of benzo(a)pyrene and risk of esophageal cancer in north of Iran

One etiologic factor for high incidence of esophageal squamous cell carcinoma (ESCC) in Golestan (Northeastern Iran) might be exposure to polycyclic aromatic hydrocarbons. We examined whether food and water are major sources of benzo(a)pyrene (BaP) exposure in this population. We used a dietary questionnaire to assess the daily intake of staple food (rice and bread) and water in 3 groups: 40 ESCC Golestan cases, 40 healthy subjects from the same area, and 40 healthy subjects from a low-risk area in Southern Iran. We measured, by high-performance liquid chromatography combined with fluorescence detection, the BaP concentration of bread, rice, and water in samples obtained from these 3 groups and calculated the daily intake of BaP. Mean BaP concentration of staple foods and water was similar and within standard levels in both areas, but the daily intake of BaP was higher in controls from the high-risk area than in controls from the low-risk area (91.4 vs. 70.6 ng/day, P < 0.01). In the multivariate regression analysis, having ESCC had no independent effect on BaP, whereas residence in the low-risk area was associated with a significant decrease in total BaP intake. Polycyclic aromatic hydrocarbons might, along with other risk factors, contribute to the high risk of ESCC in Golestan. Copyright © 2008, Taylor & Francis Group, LLC