基于PIC单片机的TCD1702C数据采集系统

图象传感器CCD在电子技术领域的应用日益广泛。本文介绍了基于PIC16F877A单片机的TCD1702C的数据采集系统,包括TCD1702C驱动电路、二值化信号处理电路及计数器法数据采集接口电路。TCD1702C驱动脉冲稳定,二值化信号处理电路简单,计数法数据采集电路可提供可靠的窗口信号,并对数据脉冲进行计数,因此可广泛地应用于目标物尺寸及位移测量。     

On nonparametric prediction of linear processes

Abstract.  We consider nonparametric prediction problem for both short- and long-range-dependent linear processes. Asymptotic properties of local linear estimates are obtained and, for long-range-dependent processes, an interesting dichotomous phenomenon is described: the limiting distribution depends on the interplay between the strength of the dependence and the magnitude of the bandwidth. A simulation study is carried out to assess the performance of the nonparametric prediction estimator.     

Criteria for dichotomy and gradient-like behavior of a class of nonlinear systems with multiple equilibria

This paper considers global properties of a class of nonlinear systems with infinite equilibria. Time-domain and frequency-domain criteria for dichotomy and gradient-like behavior are established. Similar to the sector condition in absolute stability problems, the bounded derivative condition of nonlinear functions can be used to reduce the conservativeness of the given criteria. Compared with the frequency-domain conditions, the time-domain inequalities can be solved easily by linear matrix inequality (LMI) toolbox and used to discuss controller design problems. Several examples are given to illustrate the effectiveness of the results.     

基于二分法优化理论矿体开采安全顶板厚度的预测研究

安全顶板厚度是顶板达到临界破坏状态时对应的厚度,采用二分法优化理论,对冶山铁矿下部盲矿体开采留设不同厚度尺寸的顶柱进行了模拟,得到了较为精确的安全顶板厚度,在保证矿体安全回采的同时最大限度地回收了矿产资源。     

基于二分校准的混合型数字脉宽调制器

提出了一种基于混合型数字脉宽调制器(HDPWM)的带延迟线二分法校准机制的新电路结构,能有效地提高DPWM的线性度。详细介绍了混合型DPWM的工作原理,阐述了基于二分法机制的自校准电路的整体结构。分析了该结构的后仿真结果,并与带延迟锁相环(DLL)结构的DPWM的后仿真结果相比较。在32 MHz的时钟下,该电路成功实现了开关频率为2 MHz的数字DC-DC变换器中的9-bit DPWM。该电路基于0.13μm 1.2V CMOS工艺实现,最大差分非线性(DNL)仅为0.136 LSB,积分非线性(INL)为0.15 LSB。     

考虑垫底气回收价值及资金时间价值的盐穴型地下储气库储气费计算方法

我国的地下储气库(以下简称储气库)与油气管道捆绑运营,没有单独的定价机制,计算储气库储气费时也未充分考虑资金的时间价值及油气藏型、盐穴型储气库垫底气的回收价值,导致计算结果的准确性欠佳。未来储气库实行独立、市场化运营是必然趋势,因而需要建立一种符合我国储气库运营模式的储气费定价机制。为此,以国内某盐穴型储气库建设投资项目为例,采用二分法建立了一种考虑垫底气可回收的储气费计算模型,计算出该储气库在不同内部收益率下的储气费,并分析了影响储气费的主要因素。结果表明:(1)当储气费为1.02元/m~3时,可满足内部收益率8%的要求;(2)在盐穴储气库工作气量确定的情况下,年储转次数(储气库年实际注采气量与年设计工作气量的比值)是影响储气费的最重要因素,地下及地面工程等建设投资的影响次之,而经营成本的影响最小;(3)在储转次数大于1.4时,盐穴储气库注采运行的工作效率达到最大,建议将盐穴储气库的储转次数设定为1.4。结论认为:该储气费计算方法在保证能获得一定利润的前提下,充分考虑了资金的时间价值以及垫底气的回收价值,计算得到的储气费较为合理,可推广到类似盐穴型储气库的应用计算。     

Dichotomy of solutions to discrete p-Laplace equations and p-Laplace parabolic equations

In this paper, we discuss and answer the following dichotomy problems: Let $S$ be a network and ${\Delta }_{p,\omega }$ be a discrete $p$-Laplace operator with $1<p<\infty$.(i) If $u,v$ are functions satisfying

then either $u\equiv v$ on $\overline{S}$ or $u<v$ in $S$.(ii) If $u,v$ are functions satisfying

then either $u\equiv v$ on $\overline{S}$ or $u<v$ in $S\times (0,T)$.We believe that this work is not only interesting in itself, but also gives a clue to solve the problems defined on the continuous domain.     

Conservative constraint satisfaction re-revisited

Conservative constraint satisfaction problems (CSPs) constitute an important particular case of the general CSP, in which the allowed values of each variable can be restricted in an arbitrary way. Problems of this type are well studied for graph homomorphisms. A dichotomy theorem characterizing conservative CSPs solvable in polynomial time and proving that the remaining ones are NP-complete was proved by Bulatov (2003) in [4]. Its proof, however, is quite long and technical. A shorter proof of this result based on the absorbing subuniverses technique was suggested by Barto (2011) in [1]. In this paper we give a short elementary proof of the dichotomy theorem for conservative CSPs.     

Combining binary classifiers in different dichotomy spaces for text categorization

Several supervised machine learning applications are commonly represented as multi-class problems, but it is harder to distinguish several classes rather than just two classes. In contrast to the approaches one-against-all and all-pairs that transform a multi-class problem into a set of binary problems, Dichotomy Transformation (DT) converts a multi-class problem into a different problem where the goal is to verify if a pair of documents belongs to the same class or not. To perform this task, DT generates a dichotomy set obtained by combining a pair of documents, each belongs to either a positive class (documents in the pair that have the same class) or a negative class (documents in the pair that come from different classes). The definition of this dichotomy set plays an important role in the overall accuracy of the system. So, an alternative to avoid searching for the best dichotomy set is using multiple classifier systems because we can have many different sets where each one is used to train one binary classifier instead of having only one dichotomy set. Herein we propose Combined Dichotomy Transformations (CoDiT), a Text Categorization system that combines binary classifiers that are trained with different dichotomy sets using DT. By using DT, the number of training examples increases exponentially when compared with the original training set. This is a desirable property because each classifier can be trained with different data without reducing the number of examples or features. Therefore, it is possible to compose an ensemble with diverse and strong classifiers. Experiments using 14 databases show that CoDiT achieves statistically better results in comparison to SVM, Bagging, Random Subspace, BoosTexter, and Random Forest.     

Rethinking dichotomization: A critical perspective on the use of “hard” and “soft” in project management research

This paper elaborates on the categorization – dichotomization – between “hard” and “soft” in project management research. This categorization is becoming more increasingly used in project management research for example by stating that some projects are “hard”, while other projects are “soft”, that some project skills are “hard”, while other project skills are “soft” etc. The aim is to discuss this dichotomization as an example of hierarchization – a power struggle between opposites – within project management research and literature and acknowledge the effects for project management research and practice of unreflective upholding of this dichotomy. We provide a critical review and discussion of stage-gate models as an example of “hard” project management approaches, and agile methods as an example of “soft” approaches to project management and acknowledge that in project management practice, it seems as if “hard” and “soft” approaches are most often combined. Hence, this dichotomy seems to be upheld by the research community while practitioners show a more holistic perspective to project management.