基于“系统化教学载体设计”的人才培养方案研究与实践

为适应当今职业教育的发展,对人才培养方案深入研究和改革创新成为重要课题。为提高工程技术类专业人才培养质量,切实提高学生实际动手能力,文章依据系统理论,从实用性和可操作性出发,把系统化教学载体作为整体研究对象,从载体的技术选型和设计开发、新型课程体系建设着手,创新性地提出"基于系统化教学载体设计"的人才培养方案,并以机电一体化技术专业为例,具体呈现该培养方案的实施办法。

“总载体”平台上的课程体系设计

"总载体"是系统化教学载体,是一种贯穿人才培养全过程,承载起学生知识学习、技能训练、综合技术应用等系统化的教学载体。基于"总载体"平台设计的课程体系,能有效弥补工程技术类专业现行人才培养方案的不足之处,切实提高学生技术技能。通过对机电一体化技术专业在"总载体"平台上的课程体系设计进行深入研究,力图探索出基于"总载体"平台的课程开发及"总载体"选择的一般规律。

A novel frequency synchronization scheme for OFDM systems

A novel frequency synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed, including a novel frequency offset estimation algorithm and a novel frequency offset compensation algorithm. The frequency offset estimation includes both the fractional frequency offset (FFO) estimation and the integral frequency offset (IFO) estimation. Firstly, the FFO was obtained by the conventional ML algorithm in time domain. After the FFO was compensated in time domain, the IFO was obtained by the proposed algorithm based on the energy of virtual carriers. This algorithm needs only simple calculations and has a large frequency offset estimation range. Furthermore, it is insensitive to symbol synchronization errors and channel changing. Finally, the IFO was compensated based on the carrier-positions offset, which can be completed through carrier-positions cyclic shifts in frequency domain. This proposed frequency synchronization scheme can decrease the system redundancy without any need of assistant data, and can be applied to the fast synchronization with the only need of one OFDM symbol. The analyses and simulations show the improved performance of the proposed frequency synchronization scheme.

Branch Processes of Regular Magnetic Monopole

In this paper, by making use of Duan＇s topological current theory, the branch process of regular magnetic monopoles is discussed in detail. Regular magnetic monopoles are found generating or annihilating at the limit point and encountering, splitting, or merging at the bifurcation point and the degenerate point systematically of the vector order parameter field φ（x）. Furthermore, it is also shown that when regular magnetic monopoles split or merge at the degenerate point of field function φ, the total topological charges of the regular magnetic monopoles are stilI unchanged.

An efficient catalytic system for the synthesis of glycerol carbonate by oxidative carbonylation of glycerol

Glycerol carbonate was synthesized by the oxidative carbonylation of glycerol catalyzed by the commercial Pd/C with the aid of NaI. High conversion of glycerol （82.2%）, selectivity to glycerol carbonate （〉99%）, and TOF （900 h-1） were obtained under the conditions of 5 MPa （Pco：Po2 = 2：1）, 140 C, 2 h. The highly active palladium species were generated in situ by dissolution from the carbon support and stabilized by re-deposition onto the support surface after the reaction was finished. Palladium dissolution and re-deposition were crucial and inherent parts of the catalytic cycle, which involved heterogeneous reactions. This Pd/C catalyst could be recycled and efficiently reused for four times with a gradual decrease in activity. Moreover, the in- fluences of various parameters, e.g., types of catalysts, solvents, additives, reaction temperature, pressure, and time on the conversion of glycerol were investigated. A reaction mechanism was proposed for oxidative carbonylation of glycerol to glyc- erol carbonate.

Uncertainty analysis and probabilistic design optimization of hybrid rocket motors for manned lunar landing

To obtain a conceptual design for a hybrid rocket motor(HRM)to be used as the Ascent Propulsion System in the Apollo lunar module,the deterministic design optimization(DDO)method is applied to the HRM design.Based on the results of an uncertainty analysis of HRMs,an uncertainty-based design optimization(UDO)method is also adopted to improve the design reliability.The HRM design process,which is a multidisciplinary system,is analyzed,and a mathematical model for the system design is established to compute the motor performance from the input parameters,including the input variables and model parameters.The input parameter uncertainties are quantified,and a sensitivity analysis of the model parameter uncertainties is conducted to identify the most important model parameter uncertainties for HRMs.The DDO and probabilistic UDO methods are applied to conceptual designs for an HRM to be used as a substitute for the liquid rocket motor(LRM)of the Ascent Propulsion System.The conceptual design results show that HRMs have several advantages as an alternative to the LRM of the Ascent Propulsion System,including nontoxic propellant combination,small motor volume,and comparable functions,such as restarting and throating.Comparisons of the DDO and UDO results indicate that the UDO method achieves more robust and reliable optimal designs than the DDO method.The probabilistic UDO method can be used to develop better conceptual designs for HRMs.

Climate change and infectious diseases of wildlife： Altered interactions between pathogens, vectors and hosts

Infectious diseases result from the interactions of host, pathogens, and, in the case of vector-borne diseases, also vec- tors. The interactions involve physiological and ecological mechanisms and they have evolved under a given set of environmental conditions. Environmental change, therefore, will alter host-pathogen-vector interactions and, consequently, the distribution, in- tensity, and dynamics of infectious diseases. Here, we review how climate change may impact infectious diseases of aquatic and terrestrial wildlife. Climate change can have direct impacts on distribution, life cycle, and physiological status of hosts, pathogens and vectors. While a change in either host, pathogen or vector does not necessarily translate into an alteration of the disease, it is the impact of climate change on the interactions between the disease components which is particularly critical for altered disease risks. Finally, climate factors can modulate disease through modifying the ecological networks host-pathogen-vector systems are belonging to, and climate change can combine with other environmental stressors to induce cumulative effects on infectious dis- eases. Overall, the influence of climate change on infectious diseases involves different mechanisms, it can be modulated by phenotypic acclimation and/or genotypic adaptation, it depends on the ecological context of the host-pathogen-vector interactions, and it can be modulated by impacts of other stressors. As a consequence of this complexity, non-linear responses of disease sys- tems under climate change are to be expected. To improve predictions on climate change impacts on infectious disease, we sug- gest that more emphasis should be given to the integration of biomedical and ecological research for studying both the physio- logical and ecological mechanisms which mediate climate change impacts on disease, and to the development of harmonized methods and approaches to obtain more comparable results, as this would support the discrimination of case-specific versus gen- eral mechanisms .