浅议现行“复变函数”教材中关于“Argz”和“argz”的定义

本文对广泛使用的数学专业《复变函数论》教材中复数辐角的概念及记号进行分析,并结合教学实际提出了自己的看法。

Active Control of Structurally Radiated Sound from an Elastic Cylindrical Shell

A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) of the cylindrical shell.Both global and local control strategies were considered.The optimal control forces corresponding to each control strategy were obtained by using the linear quadratic optimal control theory.Numerical simulations were performed to examine and analyze the control performance under different control strategies.The results show that global sound attenuation of the cylindrical shell at resonance frequencies can be achieved by using point force as the control input of the ASAC system.Better control performance can be obtained under the control strategy of minimization of the radiated sound power.However,control spillover may occur at off-resonance frequencies with the control strategy of structural kinetic energy minimization in terms of the radiated sound power.Considerable levels of global sound attenuation can also be achieved in the on-resonance cases with the local control strategy,i.e.,minimization of the mean-square velocity of finite discrete locations.An ASAC experiment using an FXLMS algorithm was implemented,agreement was observed between the numerical and experimental results,and successful attenuation of structural vibration and radiated sound was achieved.

Social Causes of Arab Youth Radicalizing

The purpose of this study was to examine the impact of macro social factors （states, religion, region, Arab spring, terrorism, unrest （Shoe index）, democracy, corruption （GPI）, Human development （HDI）, low self-control, life stress events （LSE）, youth unemployment, religiosity, feeling （fear and anger）, youth unemployment and total unemployment） on Arab youth＇s radicalization. A sample of 6,730 Arab youth age 15-24 years was selected from Kuwait, UAE, KSA, Oman, Qatar, Bahrain, Jordan, Tunisia, Libya, Morocco, Lebanon, Egypt, Gaza and Palestine and Syrian refuges in Jordan. A questionnaire of 43 items to measure radicalization was developed based on the literature review. A construct validity of the scale was estimated by calculating the correlation between radicalization scale and Low self-control scale and found a positive significant relationship （0.680, a = 0.000）, a sign of validity of the scale. A Reliability of the scale is strong and was estimated by Cronbach＇s alpha and was 0.947. An average of 46.6% of the participants was categorized as radicals with standard deviation of 12. Macro social factors explained 64% of the variance on radicalization. It has a significant impact on radicalization （F = 807.6, a = 0.000）. Each single variable has a significant impact. The analysis revealed three groups of macro determinants of youth radicalization were identified： （1） Geographic factors： state, region, and Arab spring; （2） Social factors： religion, religiously, feelings, LSE and LSC; （3） Human security： unrest, terrorism, democracy, corruption, human development, youth unemployment and employment rate. To alleviate the consequences of radicalization, prevention policies should take in account youth concerns as partners and victims of radicalization. Policies need to focus on radicalization pull and push factors on micro-meso-macro level.

Beyond Logic of Discovery and Paradigmatic Consensus： A Reanalysis of the Popper-Kuhn Debate in the Philosophy of Science

There is no patina of doubt that the central philosophical theories of Karl Popper and Thomas Kuhn concerning the nature, substance and method for acquiring scientific knowledge constitute milestones in 20th century philosophy of science. Just as Popper＇s fundamental work on the subject, The Logic of Scientific Discovery, marked a decisive break with inductivist epistemologies, Kuhn＇s magnum opus, The Structure of Scientific Revolutions （1962, enlarged ed. 1970）, inaugurated the coming of age of the historical turn in the philosophy of science. Some scholars seem to consider the main doctrines of both philosophers as irreconcilables or contradictories. This explains why, for example Popper and Popperians such as Imre Lakatos and John Watkins describe themselves as ＂critical rationalists＂, whereas they refer to Kuhn as an ＂irrationalist＂ or ＂relativist＂-appellations that the latter has consistently rejected. The debate between Popper and Kuhn, especially as contained in an important work, Criticism and the Growth of Knowledge （1970）, highlights some of the knotty problems connected with philosophical appraisals of science. It also demonstrates the strengths and weaknesses of logistic approaches in the philosophy of science, on the one hand, and of historically informed socio-psychological analysis of science, on the other. In this paper, we reexamine the Popper-Kuhn controversy from an experimentalist perspective. In other words, we argue that the ideas of testing and normal science can be systematically accommodated by fine-structure dissection of empirical research through which scientists learn about the world, based on the assumption that the progress of science is the growth of experimental knowledge-a fact often neglected in theory-dominated philosophies of science. Taking discovery of the cosmic background radiation by Arno Penzias and Robert Wilson as example, the paper argues that important scientific discoveries have been accomplished even in the absence of theory in any obvious sense, a situation that conflicts with the theory-dominated models of Popper and Kuhn. Thus, it offers an account of how practicing scientists learn from research to control errors and avoid blind alleys. The paper affirms, in conclusion, that going beyond the theories of Popper and Kuhn requires that philosophers of science should take what scientists learn from experiments seriously when theorising about science, by taking into account normal testing or error detection and control strategies through which scientific knowledge is acquired and extended

思乡未得归——吴国桢在美国

国民党要员、原台湾省主席吴国桢客居美国后,思念大陆与友人.时时关心大陆的发展与祖国的命运.《邓小平文选》,他反复读过三遍,对邓小平甚为敬服.他说,中国照目前的进步下去,下一世纪,能和美国。