Disturbance and recovery of trunk mechanical and neuromuscular behaviours following prolonged trunk flexion: influences of duration and external load on creep-induced effects

Trunk flexion results in adverse mechanical effects on the spine and is associated with a higher incidence of low back pain. To examine the effects of creep deformation on trunk behaviours, participants were exposed to full trunk flexion in several combinations of exposure duration and external load. Trunk mechanical and neuromuscular behaviours were obtained pre- and post-exposure and during recovery using sudden perturbations. Intrinsic trunk stiffness decreased with increasing flexion duration and in the presence of the external load. Recovery of intrinsic stiffness required more time than the exposure duration and was influenced by exposure duration. Reflexive trunk responses increased immediately following exposure but recovered quickly (～2.5 min). Alterations in reflexive trunk behaviour following creep deformation exposures may not provide adequate compensation to allow for complete recovery of concurrent reductions in intrinsic stiffness, which may increase the risk of injury due to spinal instability. STATEMENT OF RELEVANCE: An increased risk of low back injury may result from flexion-induced disturbances to trunk behaviours. Such effects, however, appear to depend on the type of flexion exposure, and have implications for the design of work involving trunk flexion.     

Estimating the Impact of Water Pricing on Water Use Efficiency in Semi-arid Cropping System: An Application of Probabilistically Constrained Nonparametric Efficiency Analysis

By introducing proper pricing instruments, farm level water can be used more efficient. But it demands a proper estimation strategy to analyse the efficiency and the input use behavior of farms under the new pricing system. As most production relationships are stochastic in nature, excluding random errors and noise from model specifications often leads to criticism. By using a probabilistically constrained programming formulation, an empirical estimation of stochastic data envelopment analysis (DEA) is done to analyze the efficiency of irrigation water use in the agricultural production system in the Krishna river basin, India. The results illustrate that water demand is higher for farms at, or close to the frontier and lower for those with low efficiency levels. In a second step, a simulation model is developed by using the frontier and economic efficiency derived from stochastic DEA to analyse the impact of water pricing on water use efficiency and water use behaviour. It is shown that an increase in the water price would not cause sizeable profit loss, if the pricing system is administered on a volumetric basis, but water demand would decrease substantially.     

Bio-accumulation of metals on reef associated organisms of Lakshadweep Archipelago

Tissue samples of marine organisms from the coastal waters of Agatti Island were subjected to analysis of metals (cadmium, cobalt, copper, iron, magnesium, manganese, nickel, lead and zinc), using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) for the assessment of the present condition of the Island ecosystem and compiling the baseline data for future monitoring, with respect of metal accumulation of marine organisms. Tissue samples of fish, shellfish and seaweed revealed that the metals have different levels of accumulation viz. Cd = 0.08-0.14, Co = 0.01-0.02, Cu = 0.16-0.98, Fe = 3.19-5.3, Mg = 86.73-152.45, Mn = 0.17-0.55, Ni = 0.06-0.26, Pb = 0.11-0.46 and Zn = 3.26-14.2 μg g⁻¹ dry wt. Metal concentrations were more in shellfish and less in finfish. Concentrations of toxic metals such as Cd, Co, Ni and Pb were well below the permissible limits proposed by the World Health Organization.     

DEM and bathymetry estimation for mapping a tide‐coordinated shoreline from fine spatial resolution satellite sensor imagery

Fine spatial resolution remotely sensed imagery has considerable potential for mapping a shoreline. Although fine spatial resolution imagery typically allows the instantaneous shoreline to be mapped with high accuracy, interest is normally focused on a reference shoreline, defined on a stable vertical datum, which is generally not apparent in the imagery unless acquired at a time carefully coordinated with the tidal characteristics of the region. To map a tide‐coordinated shoreline, such as the mean sea level (MSL), information on terrain topography, bathymetry and tidal characteristics is required. In this study, IKONOS imagery was used to derive topographic and bathymetric information for an extract of the Malaysian coast and combined with a tide chart for the region to map the MSL. The digital elevation model (DEM) derived had a root mean square error (RMSE), calculated on independent control points, of ～2.2 m while the bathymetric model had an RMSE of 0.87 m. The shoreline derived from the combination of the DEM, bathymetry and tidal information was mapped with an RMSE of 1.8 m.     

Structural Feature and Electrochemical Performance of h-LiMnBO3 and Its Carbon Coated Material Prepared by Microwave Synthesis

采用微波合成法制备了LiMnBO3及其碳包覆材料LiMnBO3/C。考察了烧结温度和配料比对LiMnBO3结构的影响。利用XRD、SEM、HR-TEM对材料的结构和形貌进行了表征。通过恒电流充/放电性能及交流阻抗测试研究了材料的电化学性能。结果表明,实验所得LiMnBO3具有六方晶体结构(即制得h-LiMnBO3)。750℃烧结温度下,反应25 min,且nLi:nB:nMn=1:1:1时,材料结晶较为完善、晶粒细小、形貌规整。碳包覆后材料充/放电性能及电导率均有提高。LiMnBO3/C的初次放电比容量达到50.3 mAh/g。     

Spray Drying of Metal Alkoxide Sol for Strontium Titanate Ceramics

Conditions for obtaining a stable sol in an isopropyl alcohol–water medium containing titanium isopropoxide and strontium nitrate, and acetic acid as a modifier, have been described. Spray drying of the sol results in submicrometer spherical agglomerates which on further thermal decomposition yield submicrometer particles of strontium titanate at temperatures as low as 500°C. The thermal decomposition characteristics of the spray-dried precursor and the development of strontium titanate phase have been discussed. Calcined precursor powder possesses a specific surface area of 12m²/g, a comp action density of 57%, and a sintered density of > 98%. The optimum sintering temperature of such a powder was 1450°C, which resulted in a sintered grain size around 1.5 μm. Further, such a sintered sample had a dielectric constant of 260 and a loss factor of 0.008 at 1 kHz. This method appears to be very convenient with respect to handling of stable sols and thus avoids the usual difficulties regarding extended gelation as well as inhomogeneous precipitation.     

A theoretical framework for designing human-centered automotive automation systems

Increasingly sophisticated and robust automotive automation systems are being developed to be applied in all aspects of driving. Benefits, such as improving safety, task performance, and workload have been reported. However, several critical accidents involving automation assistance have also been reported. Although automation systems may work appropriately, human factors such as drivers errors, overtrust in and overreliance on automation due to lack of understanding of automation functionalities and limitations as well as distrust caused by automation surprises may trigger inappropriate human–automation interactions that lead to negative consequences. Several important methodologies and efforts for improving human–automation interactions follow the concept of human-centered automation, which claims that the human must have the final authority over the system, have been called. Given that the human-centered automation has been proposed as a more cooperative automation approach to reduce the likelihood of human–machine misunderstanding. This study argues that, especially in critical situations, the way control is handed over between agents can improve human–automation interactions even when the system has the final decision-making authority. As ways of improving human–automation interactions, the study proposes adaptive sharing of control that allows dynamic control distribution between human and system within the same level of automation while the human retains the final authority, and adaptive trading of control in which the control and authority shift between human and system dynamically while changing levels of automation. Authority and control transitions strategies are discussed, compared and clarified in terms of levels and types of automation. Finally, design aspects for determining how and when the control and authority can be shifted between human and automation are proposed with recommendations for future designs.

     

Diffusion Based Channel Gains Estimation in WSN Using Fractional Order Strategies

In this study, it is proposed that the diffusion least mean square (LMS) algorithm can be improved by applying the fractional order signal processing methodologies. Application of Caputo’s fractional derivatives are considered in the optimization of cost function. It is suggested to derive a fractional order variant of the diffusion LMS algorithm. The applicability is tested for the estimation of channel parameters in a distributed environment consisting of randomly distributed sensors communicating through wireless medium. The topology of the network is selected such that a smaller number of nodes are informed. In the network, a random sleep strategy is followed to conserve the transmission power at the nodes. The proposed fractional order modified diffusion LMS algorithms are applied in the two configurations of combine-then-adapt and adapt-then-combine. The average squared error performance of the proposed algorithms along with its traditional counterparts are evaluated for the estimation of the Rayleigh channel parameters. A mathematical proof of convergence is provided showing that the addition of the nonlinear term resulting from fractional derivatives helps adjusts the autocorrelation matrix in such a way that the spread of its eigenvalues decreases. This increases the convergence as well as the steady state response even for the larger step sizes. Experimental results are shown for different number of nodes and fractional orders. The simulation results establish that the accuracy of the proposed scheme is far better than its classical counterparts, therefore, helps better solves the channel gains estimation problem in a distributed wireless environment. The algorithm has the potential to be applied in other applications related to learning and adaptation.     

Conditional mean- and median-based cumulative sum control charts for Weibull data

This article deals with the monitoring of censored data using the cumulative sum (CUSUM) control charts for Weibull lifetimes under type-I censoring. To develop an efficient CUSUM structure for censored data, we use the conditional expected value (CEV) and conditional median (CM) approaches. In particular, we focus on the detection of shifts in the mean of Weibull lifetimes assuming censored data. In addition to fixed/known parameter values, the effect of estimation is assessed on the detection power of control charts. The performance of the proposed charts is evaluated by the average run length (ARL). Furthermore, the ARL performance of CUSUM charts is compared with CEV- and CM-based exponentially weighted moving average (EWMA) control charts. Besides an extensive simulation study, the significance of the current work is illustrated by a data set on the response time of a thermostat experiment.