Robust spectral estimation for speed of sound with phase shift correction applied online in yeast fermentation processes

Ultrasound techniques are well suited to provide real‐time characterization of bioprocesses in non‐invasive, non‐contact, and non‐destructive low‐power consumption measurements. In this paper, a spectral analysis method was proposed to estimate time of flight (TOF) between the propagated echoes, and its corresponding speed of sound (USV). Instantaneous power spectrum distribution was used for accurate detection of echo start times, and phase shift distribution for correcting the involved phase shifts. The method was validated by reference USV for pure water at 9–30.8°C, presenting a maximum error of 0.22%, which is less than that produced by the crosscorrelation method. Sensitivity analyses indicated a precision of 6.4 × 10^?3% over 50 repeated experiments, and 0.11% over two different configurations. The method was competently implemented online in a yeast fermentation process, and the calculated USV was combined with temperature and nine signal features in an artificial neural network. The network was designed by back propagation algorithm to estimate the instantaneous density of the fermentation mixture, producing a maximum error of 0.95%.     

Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations

We present simulation results for the volume expansivity, isothermal compressibility, isobaric heat capacity, Joule-Thomson coefficient and speed of sound for carbon dioxide (CO 2 ) in the supercritical region, using the fluctuation method based on Monte Carlo simulations in the isothermal-isobaric ensemble. We model CO 2 as a quadrupolar two-center Lennard-Jones fluid with potential parameters reported in the literature, derived from vapor-liquid equilibria (VLE) of CO 2 . We compare simulation results with an equation of state (EOS) for the two-center Lennard-Jones plus point quadrupole (2CLJQ) fluid and with a multiparametric EOS adjusted to represent CO 2 experimental data. It is concluded that the VLE-based parameters used to model CO 2 as a quadrupolar two-center Lennard-Jones fluid (both simulations and EOS) can be used with confidence for the prediction of thermodynamic properties, including those of industrial interest such as the speed of sound or Joule-Thomson coefficient, for CO 2 in the supercritical region, except in the extended critical region.     

CT增强对比剂的不同浓度和流速对肾脏增强图像质量的影响

目的：探讨128排螺旋CT扫描增强对比剂的不同浓度和流速对肾脏增强图像质量的影响。方法：回顾性分析2011年7月~2013年5月间于我院影像科行腹部增强CT扫描检查的患者136例,对采用不同浓度（300 mgI/mL、350 mgI/mL）和不同流速（3 mL/s、5 mL/s）的图像质量,选取选取左肾动脉开口处腹主动脉（D）、左/右肾脏动脉（E）、左/右肾脏静脉（F）、左/右肾皮质（G）、左/右肾实质（H）作为感兴区进行分析,评估碘海醇浓度及流速增强剂对图像质量的影响。结果：不同浓度相同流速增强剂对图像质量的影响比较：左肾动脉开口处腹主动脉、肾脏动脉、肾脏静脉血管显影质量比较差异无统计学意义,P〉0.05;肾皮质、肾实质差异有统计学意义,P〈0.05;相同浓度不同流速增强剂对图像质量的影响差异各部位均有统计学意义,均P〈0.05。结论：较高碘海醇使用浓度和较快的注射流速对肾脏血流显影有帮助,因此,在安全剂量范围内,适当增加碘海醇使用浓度及增加对比剂的注射速度会提高肾脏增强扫描的图像质量。     

基于Matlab的鱼类游泳动力学分析

鱼类游泳动力学分析研究对解决鱼道等工程应用中水力学设计方面的关键问题有着重要的意义,利用计算机技术对鱼类游泳动力学进行分析有助于研究目标鱼类的生理特性、游泳能力及其与水力环境因子的响应关系。基于MATLAB软件对我国特有鱼类鲢幼鱼进行游泳动力学分析,借助鲢幼鱼游泳时的摆尾行为,得到不同水流速度下鲢幼鱼的摆尾频率、摆尾幅度、游泳速度和加速度;对比人工计数和手动跟踪分析方法,从实际操作复杂程度和实验数据准确性的角度,分析各数据采集方法的优劣性。结果表明基于Matlab软件采用跟踪鱼的身体中线的思路能更高效的获取大量的运动参数,比如摆尾频率、摆尾幅度、游泳速度和加速度等指标。文章介绍了一种基于Matlab开发的鱼类游泳动力学分析方法,有助于为以后鱼类游泳动力学研究提供依据。     

Enhanced competitiveness for nodulation of Medicago sativa by Rhizobium meliloti transconjugants harbouring the root-inducing plasmids of Agrobacterium rhizogenes strain 15834

Abstract The root-inducing plasmid of Agrobacterium rhizogenes strain 15834 marked with transposon Tn 5 -mob RP4-4 with a helper plasmid was mobilized into nitrogen-fixing Rhizobium meliloti strain CIAM 1759. The resulting transconjugants did not induce ‘hairy’ root syndrome but developed nitrogen-fixing nodules on alfalfa. Among the 9 transconjugants tested, 6 strains had increased modulation rates. The competitiveness of 2 of these R. meliloti (pRi) strains was significantly enhanced as compared with the parent strain CIAM 1759; this was confirmed both in tube and in pot tests.     

Design and verification of a simple 3D dynamic model of speed skating which mimics observed forces and motions

Advice about the optimal coordination pattern for an individual speed skater, could be addressed by simulation and optimization of a biomechanical speed skating model. But before getting to this optimization approach one needs a model that can reasonably match observed behaviour. Therefore, the objective of this study is to present a verified three dimensional inverse skater model with minimal complexity, which models the speed skating motion on the straights. The model simulates the upper body transverse translation of the skater together with the forces exerted by the skates on the ice. The input of the model is the changing distance between the upper body and the skate, referred to as the leg extension (Euclidean distance in 3 D space). Verification shows that the model mimics the observed forces and motions well. The model is most accurate for the position and velocity estimation (respectively 1.2% and 2.9% maximum residuals) and least accurate for the force estimations (underestimation of 4.5–10%). The model can be used to further investigate variables in the skating motion. For this, the input of the model, the leg extension, can be optimized to obtain a maximal forward velocity of the upper body.     

Strategy quantification using body worn inertial sensors in a reactive agility task

Agility performance is often evaluated using time-based metrics, which provide little information about which factors aid or limit success. The objective of this study was to better understand agility strategy by identifying biomechanical metrics that were sensitive to performance speed, which were calculated with data from an array of body-worn inertial sensors. Five metrics were defined (normalized number of foot contacts, stride length variance, arm swing variance, mean normalized stride frequency, and number of body rotations) that corresponded to agility terms defined by experts working in athletic, clinical, and military environments. Eighteen participants donned 13 sensors to complete a reactive agility task, which involved navigating a set of cones in response to a vocal cue. Participants were grouped into fast, medium, and slow performance based on their completion time. Participants in the fast group had the smallest number of foot contacts (normalizing by height), highest stride length variance (normalizing by height), highest forearm angular velocity variance, and highest stride frequency (normalizing by height). The number of body rotations was not sensitive to speed and may have been determined by hand and foot dominance while completing the agility task. The results of this study have the potential to inform the development of a composite agility score constructed from the list of significant metrics. By quantifying the agility terms previously defined by expert evaluators through an agility score, this study can assist in strategy development for training and rehabilitation across athletic, clinical, and military domains.     

Diverse speed response properties of motion sensitive neurons in the fly’s optic lobe

Speed and acceleration are fundamental components of visual motion that animals can use to interpret the world. Behavioral studies have established that insects discriminate speed largely independently of contrast and spatial frequency, and physiological recordings suggest that a subset of premotor descending neurons is in this sense speed-selective. Neural substrates and mechanisms of speed selectivity in insects, however, are unknown. Using blow flies Phaenicia sericata, intracellular recordings and dye-fills were obtained from medulla and lobula complex neurons which, though not necessarily speed-selective themselves, are positioned to participate in circuits that produce speed-selectivity in descending neurons. Stimulation with sinusoidally varied grating motion (0–200°/s) provided a range of instantaneous velocities and accelerations. The resulting speed response profiles are indicative of four distinct speed ranges, supporting the hypothesis that the spatiotemporal tuning of mid-level neurons contains sufficient diversity to account for the emergence of speed selectivity at the descending neuron level. This type of mechanism has been proposed to explain speed discrimination in both insects and mammals, but has seemed less likely for insects due to possible constraints on small brains. Two additional recordings are suggestive of acceleration-selectivity, a potentially useful visual capability that is of uncertain functional significance for arthropods.     

Stopping rule of host search by the parasitoid,Chrysocharis pentheus (Hymenoptera: Eulophidae), in host patches

We studied the stopping rule obeyed by the female parasitoid, Chrysocharis pentheus, in deciding when to leave the leaflet on which she is searching for larvae of Phytomyza ranunculi. She seemed not to employ some stopping rules that have been suggested; i.e., a fixed-number rule and a fixed-time rule and others. The stopping model formulated for Dapsilarthra rufiventris parasitic on the same host species fitted well to the results. The model assumes that the searching female will deposit a marking pheromone on the leaflet at a rate proportional to the search speed and will leave the leaflet when the amount of the pheromone that has accumulated on the leaflet reaches the threshold, L. In this model, L denotes the amount of search effort spent on the leaflet. A comparison of the observed results with the predictions from the model suggested that L increased markedly at the first encounter with the mine (host), but less at later encounters. C. pentheus appears to employ a mixed strategy of a fixed search-effort and an area-concentrated search. This would confer an adaptive advantage in foraging for P. ranunculi larvae, which are distributed in clumps among leaflets in the field.