Physiological strains in hot-humid conditions while wearing disposable protective clothing commonly used by the asbestos removal industry

Abstract

The purpose of this study is to investigate workers' responses to work in hot-humid conditions while wearing protective clothing commonly used by the asbestos removal industry, and to evaluate the effects of resting between work bouts in a cool environment on the physiological strain. Seven male students wearing impermeable protective clothing and air masks were exposed to the following conditions for 100 min on separate days: (1) hot conditions (35°C/85%RH), (2) cool conditions (20°C/85%RH), and (3) hot/cool conditions (working in hot conditions and resting in cool conditions). After 12 min rest, the subjects worked on an ergometer (70 Watts) for 18 min. This experimental schedule was repeated three times under each environmental condition. Rectal temperature (T_π), heart rate (HR), sweat rate (SR) and discomfort sensation were recorded. Two of the subjects were not able to complete the experiment in hot conditions. The increases in T_π and HR with time were not found in cool conditions. Although T_π increased in hot/cool conditions, it was almost half of that in hot conditions. Since HR did not return to the pre-work level during recovery in hot conditions, HR during work was accompanied by increases in HR at pre-work. HR during work in hot/cool conditions was higher than that in cool conditions, HR at pre-work, however, was almost the same as that in cool conditions because of rapid recovery. The means of SR in hot and hot/cool conditions were five and four times greater than that in cool conditions, respectively. Discomfort sensation was improved by resting in cool conditions either at rest in cool conditions or during work in hot conditions. The rate of body heat storage that was calculated at the end of each work and recovery period showed that it was positive even in recovery under the hot conditions. It also presented a significant negative phase in recovery under the hot/cool conditions. Thermal stress was linked to work in protective clothing in hot-humid environments. However, the physiological strains were dramatically ameliorated by resting between work periods in a cool environment. The idea of a ‘cool room’ inside the workplace, so to reduce thermal stress, is proposed.     

Direct equivalence between geometric conditions and algebraic conditions for discrete-time nonlinear observer

Unlike the continuous-time case, algebraic necessary and sufficient conditions for a single output discrete-time system to be state equivalent to a nonlinear observer canonical form have been found and are easier to verify for those who are not accustomed to differential geometry. The geometric conditions look very different from the algebraic conditions. In this paper, we show direct equivalence of the geometric conditions and the algebraic conditions in order to enhance the understanding of the geometric conditions.     

First-order and second-order necessary conditions for optimality of singular controls

The derivation of necessary conditions for the optimality of singular controls (in the sense of Pontryagin's maximum principle) in optimal control problems is inves- tigated. A new class of the necessary conditions is developed. This class of necessary conditions is composed of two parts, the first-order and second-order necessary conditions. As an application of these necessary conditions, an illustrative example is given, which shows that the necessary conditions developed are stronger than the generalized Legendre-Clebsch condition. That is, the singular control in the example satisfies the generalized Legendre-Clebsch condition, but does not satisfy the necessary conditions developed in this paper.     

Generalized sampled data feedback control of distributed parameter systems

In the sampled-data control literature there are necessary conditions and sufficient conditions for stabilizability of distributed parameter systems by generalized sampled-data control. For finite-dimensional systems the necessary conditions are also known to be sufficient. We show that this equivalence extends to the infinite-dimensional case if the underlying semigroup is analytic. However, for general systems, the necessary conditions are not sufficient, nor are the sufficient conditions necessary. We prove this by a single example with a free parameter – one choice of parameter shows that the necessary conditions are too weak, and another choice shows that the sufficient conditions are too strong.     

Generalized sampled data feedback control of distributed parameter systems

In the sampled-data control literature there are necessary conditions and sufficient conditions for stabilizability of distributed parameter systems by generalized sampled-data control. For finite-dimensional systems the necessary conditions are also known to be sufficient. We show that this equivalence extends to the infinite-dimensional case if the underlying semigroup is analytic. However, for general systems, the necessary conditions are not sufficient, nor are the sufficient conditions necessary. We prove this by a single example with a free parameter – one choice of parameter shows that the necessary conditions are too weak, and another choice shows that the sufficient conditions are too strong.     

Sufficient conditions for optimal controls—use of generalized convexity†

Several sufficient conditions for optimality are presented. These conditions are made of necessary conditions sufficiently strengthened with convexity and generalized convexity assumptions. The use of generalized convexity concepts allows one to obtain conditions weaker than some sufficient conditions previously obtained with convexity.     

GIS中文查询语句的查询条件语义抽取

无论多么复杂的查询语句都是由查询目标和查询条件组成的，查询条件决定着查询语句的结构，查询条件之间可以是并列的，也可以是嵌套的，查询条件的顺序也不是固定的。本文采取信息抽取的原理来抽取查询条件语义信息，提出了抽取查询条件语义信息的算法，这些算法可形成中文查询语句的各种类型的查询条件。实验表明，这些算法可以
以有效地抽取查询条件语义信息。     

New Robust Stability Conditions and Design of Robust Stabilizing Controllers for Takagi–Sugeno Fuzzy Time-Delay Systems

In this paper, we consider robust stability and stabilization of uncertain Takagi-Sugeno fuzzy time-delay systems where uncertainties come into the state and input matrices. Some stability conditions and robust stability conditions for fuzzy time-delay systems have already been obtained in the literature. However, those conditions are rather conservative and do not guarantee the stability of a wide class of fuzzy systems. This is true in case of designing stabilizing controllers for fuzzy time-delay systems and it thus leads to a conservative fuzzy controller design as well. We first consider rather relaxed robust stability conditions of uncertain fuzzy systems. To this end, we introduce an auxiliary system to the original fuzzy time-delay system to obtain generalized delay-dependent stability conditions. Such an auxiliary system has some arbitrary matrices that generalize not only the system representation but also delay-dependent stability conditions. Conditions we obtain here are delay-dependent conditions that depend on the upper bound of time-delay, and are given in terms of linear matrix inequalities (LMIs). Then, we compare our delay-dependent stability conditions with other conditions in the literature, and show that our conditions guarantee the stability of a wider class of systems than others. Next, we consider the robust stabilization problem with memoryless and delayed state feedback controllers. Based on our generalized robust stability conditions, we obtain delay-dependent sufficient conditions for the closed-loop system to be robustly stable, and give a design method of robustly stabilizing controllers. Finally, we give three examples that illustrate our results.     

A sufficiency condition for discrete time optimal processes†

Sufficient conditions for optimality of a class of linear discrete time processes are presented. In distinction to previously obtained necessary conditions for optimality, these sufficient conditions hold under very weak hypotheses. An example, which might arise in a sampled data system, is presented. For the example the sufficient conditions yield the optimal control, but the necessary conditions are not applicable since the required hypotheses are not satisfied.     

Weak imposition of Dirichlet boundary conditions in fluid mechanics

Weakly enforced Dirichlet boundary conditions are compared with strongly enforced conditions for boundary layer solutions of the advection-diffusion equation and incompressible Navier-Stokes equations. It is found that weakly enforced conditions are effective and superior to strongly enforced conditions. The numerical tests involve low-order finite elements and a quadratic NURBS basis utilized in the Isogeometric Analysis approach. The convergence of the mean velocity profile for a turbulent channel flow suggests that weak no-slip conditions behave very much like a wall function model, although the design of the boundary condition is based purely on numerical, rather than physical or empirical, conditions.     

Robust stability and stabilizing controller design of fuzzy systems with discrete and distributed delays

In this paper, we consider delay-dependent stability conditions of Takagi-Sugeno fuzzy systems with discrete and distributed delays. Although many kinds of stability conditions for fuzzy systems with discrete delays have already been obtained, almost no stability condition for fuzzy systems with distributed delays has appeared in the literature. This is also true in case of the robust stability for uncertain fuzzy systems with distributed delays. Here we employ a generalized Lyapunov functional to obtain delay-dependent stability conditions of fuzzy systems with discrete and distributed delays. We introduce some free weighting matrices to such a Lyapunov functional in order to reduce the conservatism in stability conditions. These techniques lead to generalized and less conservative stability conditions. We also consider the robust stability of fuzzy time-delay systems with uncertain parameters. Applying the same techniques made on the stability conditions, we obtain delay-dependent sufficient conditions for the robust stability of uncertain fuzzy systems with discrete and distributed delays. Moreover, we consider the state feedback stabilization. Based on stability and robust stability conditions, we obtain conditions for the state feedback controller to stabilize the fuzzy time-delay systems. Finally, we give two examples to illustrate our results. Delay-dependent stability conditions obtained here are shown to guarantee a wide stability region.     

多智能体网络系统的能控性代数条件

能控性是多智能体系统研究的核心问题,主要包括结构可控性和精准可控性。对多智能体系统的模型和能控性代数条件进行了总结。在相对协议和绝对协议条件下,运用图论和矩阵论的知识系统分析了多智能体系统能控性的代数条件。按照同质多智能体到异质多智能体的顺序,对现有的多智能体系统模型和代数条件进行了梳理,并在已有结论的基础上对多智能体系统能控性的代数条件进行了改善,进一步提出了新的代数条件。多智能体能控性代数条件的改进大大简化了能控性的计算量。     

On stabilizing receding horizon controls for linear continuoustime-invariant systems

In this paper, new matrix inequality conditions on the terminal weighting matrices are proposed for linear continuous time-invariant systems under which nonincreasing or nondecreasing monotonicities of the optimal cost are guaranteed. It is shown that the proposed terminal inequality conditions guarantee the closed-loop stability of the receding horizon control with additional conditions of observability or controllability. The proposed terminal inequality conditions for the cost monotonicity and the closed-loop stability include most well-known existing terminal conditions as special cases     

粒子群优化算法边界条件研究

粒子群优化算法在搜索全局最优过程中,粒子可能超出界限。针对该情况,提出5种新的受限制的边界条件,将出界粒子随机置于搜索空间内。通过基准函数将这5种边界条件与原有的6种边界条件进行对比测试,并从全局最优和收敛速度两方面对仿真结果进行分析,结果表明,新提出的随机重置的边界条件其性能明显优于置于边界的情况,无形/吸收的边界条件也稍优于其他不受限制的边界条件。     

On delay-dependent stability for vector nonlinear stochastic delay-difference equations with Volterra diffusion term

Global asymptotic stability conditions for discrete vector nonlinear stochastic systems with state delay and Volterra diffusion term are obtained based on the convergence theorem for semimartingale inequalities, without assuming the Lipschitz conditions for nonlinear drift functions. The derived stability conditions are directly expressed in terms of the system coefficients. A number of nontrivial examples of nonlinear systems satisfying the obtained stability conditions are given. The obtained results are compared to some previously known asymptotic stability conditions for discrete nonlinear stochastic systems.     

形状插值的G1 Hermite曲线

提出了在给定2个端点及其切矢方向的条件下生成一条形状较好的三次Hermite曲线的方法.把未知的形状最好曲线的端点切矢模长看作端点条件的函数;然后建立该函数应当满足的条件,并根据工程制图人员在一些特殊的端点条件下的绘图得到一些经验数据;最后把该函数近似用三角函数的二次以下谐波分解表示,根据已有的经验数据和建立的条件得到谐波分量的大小.目标曲线的计算简单,在经验数据的情况下,目标曲线端点切矢模长范围为(0.5,2.9).与已有方法相比,曲线形状较好.     

一种基于BPNN和SVM-PDE的旋转机械变工况预警方法

针对传统固定报警限未考虑时变工况的影响,易造成设备在高工况下虚警、低工况下漏警的问题,提出了一种基于BPNN(BP神经网络)和SVM-PDE(支持向量机概率密度估计)的旋转机械变工况故障预警方法.利用BPNN识别设备运行工况,结合信号处理方法从各工况振动数据中提取出多维特征并利用PCA(主成分分析)约简特征维度.将传统支持向量机(SVM)核函数改造为概率密度函数,将运行工况和低维特征输入SVM求解不同工况下正常样本的概率密度.以各个工况下正常样本概率密度值的边界值作为振动阈值进行故障预警.利用双转子试验台振动数据进行验证,结果表明,相较于固定阈值预警方法,基于BPNN和SVM-PDE的旋转机械变工况预警方法能有效降低漏警率和虚警率,验证了该方法的有效性.     

Observer design for systems with time-delayed states

Recently, the conditions of observers that can estimate directly Kx(t) for an arbitrarily given K, and that are free of the effect of time delayed states of the system, are formulated. This paper points out that, because of the equivalence in formulation, the existing conditions for unknown input observers can be used to establish directly a new set of sufficient conditions for that recent observer. This new set of sufficient conditions is much simpler, and therefore much more useful and significant, than the sufficient conditions derived in that recent paper. This new set of sufficient conditions also reveals some basic mistakes of that recent paper. In addition, this paper reveals the severe restrictiveness of this new set of conditions and proposes a fundamentally new observer design formulation that can relax that set of conditions significantly.