基于GA-BP神经网络的扬声器音盆性能预测技术

在电声零器件制造行业中,扬声器音盆的性能好坏直接关系到扬声器产品的质量.本文提出用遗传算法(GA)优化BP神经网络模型对扬声器音盆性能进行预测.在分析了BP神经网络原理的基础上,主要阐述了如何应用遗传算法优化BP神经网络,以改进BP神经网络收敛速度慢、易陷入局部极小值的缺点.针对音盆产品特点,建立音盆性能的GA-BP神...     

Above a swamp: A theory of high-quality scientific production

We elaborate a model of the incentives of scientists to perform activities of control and criticism when these activities, just like the production of novel findings, are costly, and we study the strategic interaction between these incentives. We then use the model to assess policies meant to enhance the reliability of scientific knowledge. We show that a certain fraction of low-quality science characterizes all the equilibria in the basic model. In fact, the absence of detected low-quality research can be interpreted as the lack of verification activities and thus as a potential limitation to the reliability of a field. Incentivizing incremental research and verification activities improves the expected quality of research; this effect, however, is contrasted by the incentives to free ride on performing verification if many scientists are involved, and may discourage scientists to undertake new research in the first place. Finally, softening incentives to publish does not enhance quality, although it increases the fraction of detected low-quality papers. We also advance empirical predictions and discuss the insights for firms and investors as they “scout” the scientific landscape.     

提高学生综合能力与素质的课堂教学改革探索

课堂教学是开展大学生素质教育的主阵地,在学生综合能力培养和素质提升方面具有重要作用。目前工科的专业课堂教学中存在诸多问题,严重制约和影响了人才培养目标的实现和人才培养质量的提高。该文以提高工科学生综合能力和素质为目标,针对专业课堂教学存在的问题,开展了深入的课堂教学改革研究与实践活动,经过探索,提出了相应的解决方法和具体措施。经过实践验证,该文提出的课堂教学改革方法与措施,切实可行,行之有效,可为工科的专业课堂教学改革提供参考与借鉴。     

关联理论下大学生英语口语实践能力的培养——以应用型本科院校为例

关联理论认为,成功交际的关键在于说话人和受话人能否找到最佳关联。合理地运用关联性在语言交际之中。会让我们更加真实地理解说话人所要表达的交际意图,更加准确地把握说话人的交际目的,从而使交际整个过程更加顺利。生动而有效的大学英语口语教学就应该注重这些语言交际的规律,并在教学的过程中合理地加以运用,循序渐进地引导学生培养和锻炼英语口语实践能力。本文以应用型本科院校为例,探讨了应用性本科院校大学英语口语课堂中如何运用关联理论培养大学生英语口语实践能力的具体举措。     

基于FPGA的SoC/IP验证平台的应用

基于FPGA的验证平台能够缩短SoC芯片的开发时间,提高验证工作的可靠性,并具有可重用性。利用Xilinx公司的FPGA作为一个基于标准总线连接的IP模块验证平台,并将待验证IP模块综合后下载于FPGA中,通过软硬件协同验证的方法,验证了待测IP模块的正确性。通过介绍SPI模块的验证方法,给出了基于FPGA的SoC/IP验证的软件设计思路。     

Investigation of array robustness to sensor failure

The presence of uncertainties in the array response, due to sensors operational malfunctions and environmental effects, results in a performance degradation often greater than the application requirements can afford. Various attempts have been made to measure the effect of the presence of uncertainties on the performance of direction-finding (DF) algorithms and, moreover, several methods have been developed to either detect or partly rectify the resulting defects in performance and hence improve the robustness of the array system. However, the impact of sensor response uncertainties on the ultimate array DF capabilities, as they are determined by the array manifold characteristics, has not been considered thoroughly. In this paper, the sensitivity of array DF capabilities to sensor response errors is first formulated and investigated. Robustness and reliability measures are then proposed. Such measures can be used as tools for the evaluation of each sensor's importance within the array geometry and as criteria for the comparison of a number of array geometries.     

Test theory for evaluating reliability of IR test collections

Classical test theory offers theoretically derived reliability measures such as Cronbach’s alpha, which can be applied to measure the reliability of a set of Information Retrieval test results. The theory also supports item analysis, which identifies queries that are hampering the test’s reliability, and which may be candidates for refinement or removal. A generalization of Classical Test Theory, called Generalizability Theory, provides an even richer set of tools. It allows us to estimate the reliability of a test as a function of the number of queries, assessors (relevance judges), and other aspects of the test’s design. One novel aspect of Generalizability Theory is that it allows this estimation of reliability even before the test collection exists, based purely on the numbers of queries and assessors that it will contain. These calculations can help test designers in advance, by allowing them to compare the reliability of test designs with various numbers of queries and relevance assessors, and to spend their limited budgets on a design that maximizes reliability. Empirical analysis shows that in cases for which our data is representative, having more queries is more helpful for reliability than having more assessors. It also suggests that reliability may be improved with a per-document performance measure, as opposed to a document-set based performance measure, where appropriate. The theory also clarifies the implicit debate in IR literature regarding the nature of error in relevance judgments.     

Evaluating the generalisability of neural rumour verification models

Research on automated social media rumour verification, the task of identifying the veracity of questionable information circulating on social media, has yielded neural models achieving high performance, with accuracy scores that often exceed 90%. However, none of these studies focus on the real-world generalisability of the proposed approaches, that is whether the models perform well on datasets other than those on which they were initially trained and tested. In this work we aim to fill this gap by assessing the generalisability of top performing neural rumour verification models covering a range of different architectures from the perspectives of both topic and temporal robustness. For a more complete evaluation of generalisability, we collect and release COVID-RV, a novel dataset of Twitter conversations revolving around COVID-19 rumours. Unlike other existing COVID-19 datasets, our COVID-RV contains conversations around rumours that follow the format of prominent rumour verification benchmarks, while being different from them in terms of topic and time scale, thus allowing better assessment of the temporal robustness of the models. We evaluate model performance on COVID-RV and three popular rumour verification datasets to understand limitations and advantages of different model architectures, training datasets and evaluation scenarios. We find a dramatic drop in performance when testing models on a different dataset from that used for training. Further, we evaluate the ability of models to generalise in a few-shot learning setup, as well as when word embeddings are updated with the vocabulary of a new, unseen rumour. Drawing upon our experiments we discuss challenges and make recommendations for future research directions in addressing this important problem.     

Monitoring and Root Cause Analysis of Clinical Biochemistry Turn Around Time at an Academic Hospital

Quality can be defined as the ability of a product or service to satisfy the needs and expectations of the customer. Laboratories are more focusing on technical and analytical quality for reliability and accuracy of test results. Patients and clinicians however are interested in rapid, reliable and efficient service from laboratory. Turn around time (TAT), the timeliness with which laboratory personnel deliver test results, is one of the most noticeable signs of laboratory service and is often used as a key performance indicator of laboratory performance. This study is aims to provide clue for laboratory TAT monitoring and root cause analysis. In a 2 year period a total of 75,499 specimens of outdoor patient department were monitor, of this a total of 4,142 specimens exceeded TAT. With consistent efforts to monitor, root cause analysis and corrective measures, we are able to decreased the specimens exceeding TAT from 7–8 to 3.7 %. Though it is difficult task to monitor TAT with the help of laboratory information system, real time documentation and authentic data retrievable, along with identification of causes for delays and its remedial measures, improve laboratory TAT and thus patient satisfaction.     

基于语音识别的用户认证系统设计及其在电子商务中的应用

电子商务被更多的人们所接受的程度,在技术实现方面主要与它的安全技术、安全规范与安全系统完善程度有关.本文简要讨论了电子商务安全现状和用户认证的安全性考虑因素,着重阐述了基于语音识别的用户认证系统的设计及其在电子商务中的应用,叙述了基于说话人识别方法的用户认证系统的安全性的优点,对提高电子商务中用户认证系统的安全性能具有理论与实际意义.     

Performance reliability of high-maintenance systems

The time–history of the performance of a system is treated as a stochastic corrective process, in which deterioration due to aging is counteracted at brief maintenance checks. Using a diffusion approximation for the deterioration, simple models are proposed for describing maintenance either by component replacement or by performance restoration. Equilibrium solutions of the models show that the performance has a probability distribution with exponential tails: the uncritical use of Gaussians can grossly underestimate the probability of poor performance. The proposed models are supported by recent observational evidence on aircraft track-keeping errors, which are shown to follow the modified exponential distribution derived here. The analysis also brings out the relation between the deterioration characteristics of the system and the intensity of the maintenance effort required to achieve a given performance reliability.     

一种国Ⅳ柴油机EGR阀结焦问题研究

电控EGR阀能够更精确地控制EGR率,有效降低尾气中N0x（氮氧化物）的含量,但由于电控EGRN要求的边界使用条件较为严格,也更容易出现问题。由于EGRN对发动机的性能以及寿命有很大影响,因此发动机在开发过程中需要对EGR阀做可靠性验证试验。本文主要是以一种国四柴油机在试验过程中发生的结焦卡滞问题为案例,通过试验分析探讨EGRN结焦问题的解决办法。     

Exploiting the categorical reliability difference for binary classification

In binary pattern classification, the reliabilities of statistics obtained from the samples of the two categories are generally different. When the statistics are used for modeling a classifier, such reliability difference could impact the generalization performance. We formulate a disparity index to show the statistical disparity based on the generalized eigenvalue decomposition of the categorical moment matrices. It is shown that this disparity index can effectively indicate the reliability difference between the two categories. The obtained reliability difference is subsequently utilized to adjust the regularization term of a classifier for effective learning generalization. Our experiments based on 10 real-world benchmark data sets validate the effectiveness of the proposed method.     

Adaptive fuzzy CMAC-based nonlinear control with dynamic memory architecture

An adaptive fuzzy cerebellar model articulation controller-based (CMAC) nonlinear control with the advantage of architecture learning is proposed. To cope with the tradeoff between the complexity of CMAC architecture and the quality of system convergence, a dynamic architecture learning scheme is introduced, where the associative memory reinforcement and the associative memory reorganization are involved. In the memory reinforcement process, new associative memories will be generated when the memory cells in the current architecture are found insufficient. On the other hand, the inefficient memories will be detected and reorganized in the memory reorganization process. With the proposed approach, the task of fuzzy CMAC architecture determination by preliminary knowledge or trials can be freed when a well-organized and well-parameterized CMAC is represented to achieve desired approximation performance. Thus, with the proposed CMAC, a dynamic control approach is presented. In this paper, according to the adaptive control theory, the fuzzy CMAC (FCMAC) is utilized as the main controller to mimic the ideal computation controller and a supervisory controller is designed to compensate the approximation error. In the FCMAC, all the controller parameters are online tuned based on the Lyapunov stability theorem such that the stability of closed-loop system can be guaranteed. Simulation results and comparisons are presented for verification.     

Performance analysis of a spreading sequence estimator for spread spectrum transmissions

Direct sequence spread spectrum transmissions (DS-SS) are now widely used for secure communications, as well as for multiple access. They have many interesting properties, including low probability of interception. Indeed, DS-SS transmitters use a periodical pseudo-random sequence to modulate the baseband signal before transmission. A receiver which does not know the sequence cannot demodulate the signal.In this paper, we propose a new method which can estimate the spreading sequence in a noncooperative context. The method is based on eigenanalysis techniques. The received signal is divided into windows, from which a covariance matrix is computed. We show that the sequence can be reconstructed from the two first eigenvectors of this matrix, and that useful information, such as desynchronisation time, can be extracted from the eigenvalues.The main achievement of the present paper is a performance analysis of the proposed spreading sequence estimation procedure. An analytical approach is first considered owing to matrix perturbation theory and Wishart matrix properties. Then, complementary Monte Carlo simulations are performed to show the effectiveness of the proposed method.     

基于BP神经网络的企业突破性创新绩效评价研究

基于突破性创新的特征,借鉴传统创新绩效评价模式,从资源投入、技术产出、产品性能、过程管理、商业价值和社会价值等6个维度构建企业突破性创新绩效评价指标体系,并利用BP神经网络原理建立了企业突破性创新绩效评价模型。通过对样本企业的突破性创新绩效评价进行模型训练和仿真验证,结果表明该评价方法可信度高,模型具有较好的泛化能力。     

逻辑为纲,意在口先--浅谈逻辑结构在高职英语演讲及口语竞赛中的作用

英语演讲及口语竞赛是对大学生英语综合运用能力的全面检验。选手在赛场上的表现受到多方面因素的影响,其中,逻辑是否清晰、结构是否完整往往决定了选手的口头表现情况。本文旨在就如何在竞赛培训中增强学生的逻辑组织能力作一些探讨。     

“What is a good digital library?” – A quality model for digital libraries

In this article, we elaborate on the meaning of quality in digital libraries (DLs) by proposing a model that is deeply grounded in a formal framework for digital libraries: 5S (Streams, Structures, Spaces, Scenarios, and Societies). For each major DL concept in the framework we formally define a number of dimensions of quality and propose a set of numerical indicators for those quality dimensions. In particular, we consider key concepts of a minimal DL: catalog, collection, digital object, metadata specification, repository, and services. Regarding quality dimensions, we consider: accessibility, accuracy, completeness, composability, conformance, consistency, effectiveness, efficiency, extensibility, pertinence, preservability, relevance, reliability, reusability, significance, similarity, and timeliness. Regarding measurement, we consider characteristics like: response time (with regard to efficiency), cost of migration (with respect to preservability), and number of service failures (to assess reliability). For some key DL concepts, the (quality dimension, numerical indicator) pairs are illustrated through their application to a number of “real-world” digital libraries. We also discuss connections between the proposed dimensions of DL quality and an expanded version of a workshop’s consensus view of the life cycle of information in digital libraries. Such connections can be used to determine when and where quality issues can be measured, assessed, and improved – as well as how possible quality problems can be prevented, detected, and eliminated.     

便携式超高频射频识别读写器设计

超高频读写器的便携式设计是射频识别（RFID）系统广泛应用的关键.为实现超高频RFID读写器的便携式设计,提出一种超高频RFID读写器的设计方案.硬件系统主要包括读写器的射频前端、功率放大器、功率检测、天线阻抗调谐电路等,在设计过程中考虑信道指标并对其进行评估;在对ISO/IEC18000-6的三种协议标准进行比较的基础上选用ISO/IEC 18000-6C协议,设计相应软件系统主要包括基带模块及防冲突碰撞模块.对硬件进行评估计算并结合硬件对软件进行验证及测试,结论如下：该读写器具有功率消耗低、体积小、接口丰富等便携式优点;硬件系统性能稳定;软件功能运行良好.上述设计有效实现了射频识别系统的便携式设计.     

Solving a reliability-performance balancing problem for control systems with degrading actuators under model predictive control framework

In this paper, we formulate and study a reliability-performance balancing problem (RPBP) for long-term operational and unattended control systems with degrading actuators. It preliminarily explores a new type of autonomous maintenance method to extend the useful lifetime of the control system. The actuator, as the crucial component of a control system, executes calculated control actions and thereby is often exposed to the high-load working environment. As the actuator degrades, the control action will gradually alter with increasing magnitude to maintain the desired control performance, but this will accelerate the actuator degradation and thus reduce the useful lifetime (use reliability) of the control system. Therefore, conditionally balancing the control performance and use reliability is meaningful, for which a novel dynamic regulation strategy under the model predictive control (MPC) framework is proposed. Specifically, we model the actuator degradation using a diffusion Wiener process coupled with the control action or system state, and the corresponding actuator reliability is derived. By fusing the degradation model and system dynamics, a degradation-incorporated state space (DISS) model is formulated, in which the basic idea is to consider the actuator degradation as an extended state variable and to control it accordingly. Based on the DISS model, a mixed-index nonlinear MPC integrated with a weight tuning strategy is proposed to achieve a satisfactory balance between control performance and use reliability in the presence of actuator degradation. Further, the reference curve and the upper bound of actuator degradation are given for constructing the objective function and the constraint in the MPC optimization problem. An illustrative example is presented to demonstrate the availability of the proposed method.