风力发电对电力系统运行的影响

从风力发电对电力系统的影响入手,总结了风电网并入电网主要面临的一些技术问题,如风力发电场的规模问题,对电能质量的影响,对稳定性的影响,对保护装置的影响等;然后针对这些技术问题,综合比较了各国研究和工程技术人员在理论和实际运行方面的相关解决方案,指出各方案的优缺点,期待更成熟的风力发电技术的形成,以建设我国具有自主产权的风电产业.     

A deep learning-based method for detecting non-certified work on construction sites

The construction industry is a high hazard industry. Accidents frequently occur, and part of them are closely relate to workers who are not certified to carry out specific work. Although workers without a trade certificate are restricted entry to construction sites, few ad-hoc approaches have been commonly employed to check if a worker is carrying out the work for which they are certificated. This paper proposes a novel framework to check whether a site worker is working within the constraints of their certification. Our framework comprises key video clips extraction, trade recognition and worker competency evaluation. Trade recognition is a new proposed method through analyzing the dynamic spatiotemporal relevance between workers and non-worker objects. We also improved the identification results by analyzing, comparing, and matching multiple face images of each worker obtained from videos. The experimental results demonstrate the reliability and accuracy of our deep learning-based method to detect workers who are carrying out work for which they are not certified to facilitate safety inspection and supervision.     

An Extended Finite Variable Difference Method with Application to QUICK Scheme

A Finite Variable Difference Method (FVDM) proposed previously by the author for locally exact numerical schemes is extended so as to be applicable to polynomial expansion schemes. This extended FVDM is applied to the QUICK scheme.

The optimum differencing points are analytically derived in terms of mesh Reynolds numbers so that the variance of the numerical solution is minimized under the condition that roots of the resulting characteristic equation are nonnegative to insure the numerical stability. This optimized scheme coincides with the original QUICK scheme at Rm=8/3, which is the critical value of its stability, and complements a stable scheme for Rm greater than 8/3. This optimization improves the numerical solution for the steady and unsteady convection-diffusion equations without numerical oscillations.

In the same manner as the previous result for the locally exact numerical schemes, it has been made clear based on the extended FVDM that optimum differencing points from the view point of numerical stability and accuracy exist for the polynomial expansion schemes.     

3C认证中需要补充的质量管理体系文件

阐述了在3C认证过程中，质量管理体系文件的补充如何既能满足ISO9000标准又能涵盖工厂质量保证能力要求。     

新世纪城市住宅设计的探索

通过对我省近5年新建住宅的实态调查,提出影响本地区城市住宅建筑持续发展的制约点的重要方面,并针对这些在开发、规划、设计、建设中敏感性强、又难以解决的问题,如：日照间距不足,通风差,大进深出现大“暗厅”,住宅节能进展较慢,7至8层住宅不设电梯等问题,提出了技术设计建议。     

Maximum likelihood estimation of pseudo-stoichiometry in macroscopic biological reaction schemes

Identification of pseudo-stoichiometric (or yield) coefficients is of primary importance for building a bioprocess model. In most of the applications, the estimation of these coefficients has to be performed without any knowledge of the kinetics and on the basis of a few experiments for which noisy discrete measurements of component concentrations are available. This paper proposes maximum likelihood estimators which are able to deal with measurement errors on all the signals, at each sampling time (including the initial one) and with intrinsic sign constraints on the parameters. This kind of realistic hypotheses exclude the use of the usual (weighted) least-squares estimators. The maximum likelihood estimators are proved to be unbiased (provided a first-order approximation) and their estimation error covariance matrix can be computed (at the same level of first-order approximation). The solutions are proposed in a very general framework, dealing with cell cultures (of bacteria, yeasts or animal cells) performed in stirred tank (continuous, semi-batch or batch) reactors, and without any a priori knowledge on the kinetics. The use of the estimators and their statistical properties are illustrated in a simulation case study (fed-batch bacterial cultures) and in a real case one (batch animal cell cultures).     

Nonparametric testing against restricted alternatives under progessive censoring

Nonparametric testing procedures under progressive censoring schemes are often adopted in clinical trials and life testing experimentations. In a variety of situations, a null hypothesis (of the homogeneity of distributions) may be tested against a restricted viz., orthant or ordered alternative. Though such tests in a general setup have been considered in a complete sample or a single point censored (or truncated) experimental scheme, there has not been much progress with these tests in a progressively censored setup. Genuinely distribution free tests based on simple linear rank statistics and the classical union intersection principle are considered. The theory of such time sequential tests rests heavily on some basic invariance principles, and these are studied as well. The case of proportional hazard models is also treated briefly. The main emphasis is laid on the development of the relevant asymptotic theory, and in this context, some (sub) martingale characterizations of progressively censored rank statistics have been incorporated.     

抛物型方程的一个六阶精度的差分格式及格式稳定性的—种新的证明方法

用待定系数法构违了六阶差分格式,比已有文献的四阶差分格式提高了精度。格式稳定性的证明方法也是新的。     

Performance of integration schemes in discrete element simulations of particle systems involving consecutive contacts

In this investigation, which is a follow-up study extending earlier work (Kruggel-Emden, Sturm, Wirtz, & Scherer, 2008), a realistic assessment of the performance of integration schemes in systems of moving particles and consecutive contacts is conducted. Linear contact models are applied throughout this work as they allow for an analytical solution of consecutive oblique impacts. The many-particle systems considered are the discharge of particles from a hopper and particle movement in a shaken container. Results for many-particle systems are robust with respect to the applied integration method and step size once particle interactions are resolved with a sufficient number of steps. The integration schemes are also evaluated based on consecutive particle/wall contacts. Integration of consecutive contacts in a discrete element framework implies repeatedly solving non-continuous systems of differential equations. Various termination conditions for the normal force models and adaptive time stepping for one-step integration methods are investigated. The effect of softened contacts on particle trajectories is discussed. Based on these insights, recommendations for the most accurate integration schemes are made.