关系查询的一种原操作分解方法

提出了一种以过滤、消重、排序、归并等关系运算为查询原操作构造关系查询的思想，重点分析了多关系连接、并、交、差、除以及聚合等的分解方法及原操作构成要素．

我的操作策略

当我脑子里“揣着”几本书初涉股市之时就被完全套牢,尽管我选标的无论从业绩或是价位而言均无可挑剔,但当时大陆股市的老熊以其强有力的吼声横扫一切书中的神话。

算法时间复杂性分析综述

算法分析一方面可比较几种算法的优劣,另一方面可准确地确定编码的瓶颈。文章系统地介绍了算法时间复杂度的概念和计算方法,并对算法时间复杂度的数量级进行了分析和评价。

分析和计算算法效率的便捷方法

通过对典型算法时间效率特征的分析,将求解算法时间复杂度的复杂过程进行简化,提出按算法的不同结构特性,具体问题具体分析,采用不同的思路和策略分而治之求解.提倡将求解过程集中在时间复杂度增长率的计算上.归纳出频度统计法、频度估算法、频度未知数法、列举频度归纳法、频度期望值法、扩展递归迭代法、上下限猜测法等几种根据算法特性求解时间复杂度的方法.这些方法涵盖了大多类算法,无论是在软件设计,还是在教学实践中,都有广泛的实用价值.

《程序设计技术》教学探讨

《程序设计技术》是一门教学程序设计技术的课程。从表面上看,只要有设计计算机程序的实践经验,就能讲授这门课。但是笔者通过认真讲授这门课,发现,要讲好这门课,教学方法很重要。本文是对《程序设计技术》这门课的教学方法的一些看法,提出了《程序设计技术》教学训练流程,用来抛砖引玉。《程序设计技术》这门课的教学目的是帮助已经学过一门以上程序设计语言的学生学会设计程序,它不局限于某一种程序设计语言,要从设计计算机程序的一般意义来介绍相关技术。在准备教案时,决不能停留在对编程方法的泛泛讨论上,要使学生通过学习这门课程,搞懂编程的实质,能动手编写出他们想编写的程序。

教学实践是教学设计研究的源泉与归宿

教学设计是教育科学领域中的应用性理论与方法,教学实践应该是其研究的源泉与归宿。本文从我国基础教育课程改革的实践出发,对现有教学设计的理论与方法进行了认真的思考:分析了教学实践对教学设计的需求和教学设计在实践中所遇到的困难,提出了改进教学设计理论与方法的一些设想。

Real-time collaborative design based on operation semantics in distributed CAD environment

This paper proposes a collaborative design model based on operation semantics in a distributed computer-aided design (CAD) environment. The goal is to reduce time consumption in data format conversion and the requirement of network bandwidth so as to improve the cooperative ability and the synchronization efficiency. Firstly, real-time collaborative design is reviewed and three kinds of real-time collaborative design models are discussed. Secondly, the concept of operation semantics is defined and the framework of an operation semantics model is presented. The operation semantics carries the original design data and actual operation process to express design intent and operation activity in conventional CAD systems. Finally, according to the operation semantics model, a CAD operation primitive is defined which can be retrieved from and mapped to the local CAD system operation commands; a distributed CAD collaborative architecture based on the model is presented, and an example is given to verify the model.

ANALYSIS OF FORWARD-FLYBACK CONVERTER EMPLOYING TWO SWITCHES AND TWO TRANSFORMERS

A novel forward-flyback converter employing two switches and two transformers is presented. Two diodes of the primary side enable the voltage stress of two switches to be clamped at the input voltage ,which is lower than that of a conventional forward-flyback converter. Two transformers offer the following advantages. Firstly, the turns of primary transformer winding are reduced to half of that of a conventional forward-flyback converter with a single transformer; Secondly, the use of two transformers enables the smaller low-profile cores to be utilized, thus facilitating a low-profile design. The unequal condition of turn ratios is compared with the equal condition of turn ratios. When two turn ratios are unequal, the power distribution between the two transformers can be easily designed. Finally, experimental results verify the above analyses.

Detecting Compromised Kernel Hooks with Support of Hardware Debugging Features

Although there exist a few good schemes to protect the kernel hooks of operating systems, attackers are still able to circumvent existing defense mechanisms with spurious context infonmtion. To address this challenge, this paper proposes a framework, called HooklMA, to detect compromised kernel hooks by using hardware debugging features. The key contribution of the work is that context information is captured from hardware instead of from relatively vulnerable kernel data. Using commodity hardware, a proof-of-concept pro- totype system of HooklMA has been developed. This prototype handles 3 082 dynamic control-flow transfers with related hooks in the kernel space. Experiments show that HooklMA is capable of detecting compomised kernel hooks caused by kernel rootkits. Performance evaluations with UnixBench indicate that runtirre overhead introduced by HooklMA is about 21.5%.

Flexibility of MIP Technology

The flexibility of MIP technology to meet market demand is mainly introduced in this study. Their commercial application and technical principle are analyzed too. The MIP technology with wide feed adaptability can form a good combination with other technologies. The MIP technology has been applied extensively in China. Based on this platform, the CGP, MIP-LTG and MIP-DCR technologies have been developed, which can further improve the flexibility of MIP technology. Based on its novel reaction control technique with a sole sequential two-zone riser, the MIP users can easily switch to different operating modes between producing either more clean gasoline and propylene or diesel through changing the catalysts and varying the operating conditions. That offers MIP users with enough production flexibility and a rational production arrangement to meet the market demand. The MIP-DCR technology with less dry gas and coke yields can provide a more flexible operating mode since the catalysts to oil ratio has become an independent variable.

Model-based design method of two-axis four-actuator fast steering mirror system

This work was focused on the model-based design method of two-axis four-actuator(TAFA) fast steering mirror system(FSM), in order to improve the design efficiency. The structure and operation principle commonality of normal TAFA FSM were investigated. Based on the structure and the commonality, the conditions of single-axis idea, high-frequency resonance and coupling were modeled gradually. Combining these models, a holonomic system model was established to reflect and predict the performance of TAFA FSM. A model-based design method was proposed based on the holonomic system model. The design flow and design concept of the method were described. In accordance with the method, a TAFA FSM was designed. Simulations and experiments of the FSM were done, and the results of them were compared. The compared results indicate that the holonomic system model can well reflect and predict the performance of TAFA FSM. The bandwidth of TAFA FSM is more than 250 Hz; adjust time is less than 15 ms;overshoot is less than 8%; position accuracy is better than 10 μrad; the FSM prototype can satisfy the requirements.

Ex-situ liver surgery without veno-venous bypass

AIM:To evaluate the results of hepatic resection with ex-situ hypothermic perfusion and without veno-venous bypass.METHODS:In 3 patients with liver tumor,the degree of the inferior vena cava and/or main hepatic vein involvement was verified when the liver was dissociated in the operation.It was impossible to resect the tumors by the routine hepatectomy,so the patients underwent ex-situ liver surgery,vein cava replacement and hepatic autotransplantation without veno-venous bypass.All surgical procedures were carried out or supervised by a senior surgeon.A retrospective analysis was performed for the prospectively collected data from patients with liver tumor undergoing ex-situ liver surgery,vein cava replacement and hepatic autotransplantation without veno-venous bypass.We also compared our data with the 9 cases of Pichlmayr's group.RESULTS:Three patients with liver tumor were analysed.The first case was a 60-year-old female with a huge haemangioma located in S1,S4,S5,S6,S7 and S8 of liver;the second was a 64-year-old man with cholangiocarcinoma in S1,S2,S3 and S4 and the third one was a 55-year-old man with a huge cholangiocarcinoma in S1,S5,S7 and S8.The operation time for the three patients were 6.6,6.4 and 7.3 h,respectively.The anhepatic phases were 3.8,2.8 and 4.0 h.The volume of blood loss during operation were 1200,3100,2000 mL in the three patients,respectively.The survival periods without recurrence were 22 and 17 mo in the first two cases.As for the third case complicated with postoperative hepatic vein outflow obstruction,emergency hepatic vein outflow extending operation and assistant living donor liver transplantation were performed the next day,and finally died of liver and renal failure on the third day.Operation time(6.7 ± 0.47 h vs 13.7 ± 2.6 h) and anhepatic phase(3.5 ± 0.64 h vs 5.7 ± 1.7 h) were compared between Pichlmayr's group and our series(P = 0.78).CONCLUSION:Ex-situ liver resection and liver autotransplantation has shown a potential for treatment of complicated hepatic neoplasms that are unresectable by traditional procedures.

State of the Art and Future Trends of Unconventional PD-Measurement at Power Transformers

This paper discusses the current state of the art of diagnostics at power transformers. A special focus is set on the UHF-PD-measurement （ultra-high-frequency partial discharge measurement） because at power transformers, this diagnostic method has become more important in recent years. The current state, basics and principles of operations, proceedings as well as advantages of PD-measurement methods are covered. Furthermore problems and proposed solutions are discussed. Bushings and tap changers are not discussed in detail. In many cases, one single diagnostic method does not have the ability to sufficiently evaluate a power transformer. Therefore, a variety of diagnostic methods came up over times, which are commonly used by now. To expand the evaluation opportunities of power transformers, science strives to develop new diagnostic methods as well as to improve the existing ones. Furthermore, environmentally friendly and hardly inflammable ester liquids are examined for the use at power transformers and PD-measurement at HVDC （high voltage direct current） converter transformers as well. Potential diagnostic options and respectively current developments and findings in the field of oil-paper-insulation systems are outlined conclusively.

Computer Vision Applied to Recognition Barcodes

The bar code is one of the identification technologies used more successfully in the world. This technology was first developed as the second half of the twentieth century and quickly achieved acceptance in both industry and commerce. In this paper studies are discussed on the design, development and printing of one-dimensional barcodes of the symbologies Code 39 and Interleaved 2 of 5. There are also discussed techniques for recovering the information encoded in the bar code, which can be extended to other symbologies. The purpose of the paper is the development of an open solution with the objective to make the decoding of barcodes using computer vision techniques possible, which will be divided into four basic stages： acquisition, pre-processing, processing and presentation of results. Practical tests conducted with samples show satisfactory results, validating the operating principles of the elements involved. The proposed objective was achieved and practical tests validated the operating principles of the elements addressed by providing contribution to that segment decoding barcodes.

Analysis on performance and test of a new type of ultra-high pressure pipe joint

Analysis as well as application of ultra-high pressure hydraulic system and elements has become a trend. The structure and operation principle of a new type of ultra-high pressure pipe joint is introduced. The structure of the new type of ultra-high pressure pipe joint is simple and is easy to be produced. The finite element model on two working conditions( preload condition with 30 N·m torque and static-loading condition with 70 MPa pressure) is built and computed. The width of contact area,the equivalent stress status,as well as the contact pressure status are plotted and analyzed. According to the national standard,test on air-tightness,blasting,and cyclic endurance is conducted and the results show that the new type of ultra-high pressure pipe joint has the sealability for ultra-high pressure up to 70 MPa,and the DN6 ultra-high pressure pipe joint can provide effective seal under70 MPa fluid pressure. The research can provide a thinking and method on designing ultra-high pressure pipe joint and push forward the development of ultra-high pressure hydraulic system.

Scoping biology-inspired chemical engineering

Biology is a rich source of great ideas that can inspire us to find successful ways to solve the challenging problems in engineering practices including those in the chemical industry. Bio-inspired chemical engineering(Bio Ch E)may be recognized as a significant branch of chemical engineering. It may consist of, but not limited to, the following three aspects: 1) Chemical engineering principles and unit operations in biological systems; 2) Process engineering principles for producing existing or developing new chemical products through living ‘devices';and 3) Chemical engineering processes and equipment that are designed and constructed through mimicking(does not have to reproduce one hundred percent) the biological systems including their physical–chemical and mechanical structures to deliver uniquely beneficial performances. This may also include the bio-inspired sensors for process monitoring. In this paper, the above aspects are defined and discussed which establishes the scope of BioChE.

Evaluation of Several Phases in the Development of Management Accounting

This paper discusses three issues, raised by Relevance Lost （Johnson ＆ Kaplan, 1987）, about historical evaluation of the development of management accounting. The first issue is when management accounting system was formed; the second is how to evaluate its development in subsequent decades; the third is how to evaluate the development of practice and research of management accounting in almost twenty years after Relevance Lost was published. The role of Relevance Lost in practice and theoretical research of management accounting is widely recognized, and the disagreement with it in this paper is in the specific area of the development history of management accounting. The authors of this paper believe that the development, through having its ups and downs over time, is generally speaking a continuous process, not separated by disconnected phases, leaping from one to another. Along with the progress in practice and research, researchers and practitioners are deepening their understanding about the theoretical foundation and practical development of management accounting. The history of development of management accounting is consistent with the process people gradually understand it.

Highly Effective Brushless DC Motor in Which Unidirectional Current Flows in

Authors developed a highly effective brushless DC motor with a simple operation principle. If the operation principle of the motor is simple, a drive circuit will also become simple and its production cost will be lower. From the above fact, Minato motor was noticed. In this motor, a unidirectional current flows in the electromagnets. In other words, unidirectional windings are used. In this motor, only strong repulsive force is utilized when a permanent magnet of a rotor and an electromagnet of a stator are adjacent. Hence, torque constant becomes higher and the efficiency of the motor is high. However, an effective value of the electromagnetic current increases because a large current flows in a short period. Therefore, copper loss increases and the efficiency of the motor decreases. In order to solve above defects, a new motor is proposed. From the experiment, it is clarified that the efficiency of the proposed motor is higher than that of the commercial motors.

Selective Atom-Cavity Interaction Scheme for Quantum Controlled-NOT Gate Using Four-Level Atoms in Cavity QED System

We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum information is encoded on the stable ground states of the two atoms. During the interaction between atoms and single-mode vacuum cavity-field, the atomic spontaneous emission is negligible as the large atom-cavity detuning effectively suppresses the spontaneous decay of the atoms. The influences of the dissipation and the deviation of interaction time on fidelity and corresponding success probability of the quantum Controlled-NOT gate and the experimental feasibility of our proposal are also discussed.

Determination of Temperature-time Curve of Two Mild Moxibustion Methods:Reinforcing and Reducing

Objective： To observe the specificity of reinforcing and reducing methods of mild moxibustion and explore its clinical significance. Methods： Thirty healthy students were selected and given reinforcing of mild moxibustion on the left Neiguan （PC 6） and reducing on the right Neiguan （PC 6） respectively. Temperature of the acupoint skin surface and the temperature-time curve were recorded by a digital thermometer. Results： In application of mild moxibustion on Neiguan （PC 6）, there was a statistical difference in the temperature-increase section between reinforcing and reducing methods （P〈0.01）. The temperature-increasing section of the temperature-time curve in the reducing method was obviously steeper than that in the reinforcing method. In the period of 0.5-3 min during moxibustion, the temperature of Neiguan （PC 6） was remarkably higher in the reducing than in the reinforcing （P〈0.01）. In the application of the reducing, the time for the temperature of Neiguan （PC 6） to increase to 40~C was remarkably advanced （P〈0.05） and the rate of burning pain in the subjects was remarkably higher in the reducing method than in the reinforcing method （P〈0.001）. Conclusion： In comparison with the reinforcing method, the acupoint temperature increased more quickly in the application of reducing method and can produce obvious hot stimulation in a short period of time. In the application of the reinforcing method, the acupoint temperature increased mildly and could enhance the tolerance of the organism to the high temperature.