The analysis of the national online game industry： based on industry organization

计算机的普及与互联网的发展使得人们的生活逐渐与网络这个虚拟世界紧密结合，一些网络应用开始取代传统的娱乐方式，网络游戏便是其中最好的一例。网络游戏在国内发展至今虽只有七八年的历史，但因其发展之迅猛，以及市场规模成长之快速，引起了理论界以及学术界人士的极大的兴趣。然而，随着网络游戏的蓬勃发展，该产业也滋生了一些例如私服、外挂、虚拟财产盗窃等严重制约网游产业健康发展的问题。目前，国内网游产业链扁平化趋势明显，认清我国网游产业的市场结构、市场行为，市场绩效，寻找能有效解决私服、外挂等网游灰色问题的方法，彻底消除网游产业竞争中的不正当行为已经刻不容缓。 笔者在参考大量文献的基础上，借鉴了前人关于网游产...With the popularization of the computer and the development of internet technology, people’s lives have been integrated gradually with the web. Many network applications have gradually substituted for the traditional entertainment way, and online game is such a best case. Online game has just seven or eight year’s history in domestic development, but because of its swift development and great mark...学位：经济学硕士院系专业：经济学院经济研究所_产业经济学学号：2902006115288

Static Code Analysis and Defense Oriented to Software Security Bug

随着软件规模的日益增大，软件变得越来越复杂。各种软件安全缺陷引起了严重的安全问题，甚至造成资源的重大损失。为了降低这种风险和损失，软件开发人员在实施软件工程的过程中采取了各种手段。静态代码分析技术作为其中一种重要的手段，已经被广泛地用于查找各种软件安全缺陷。但现有的静态代码分析工具，尤其是开源工具，在分析的规模和准确性上还存在较大的问题。本文设计和实现的静态代码分析系统（ABAZER）在增大分析规模和提高准确性上都采取了有效的方法。 本文对ABAZER系统的设计和实现进行了详细的描述。 ABAZER提供了一种缺陷定义语言（BDL），使得用户能够自定义时序逻辑类型的安全缺陷。为了使缺陷定义更为准确，BDL语言还支持一定程度的值分析。ABAZER采用控制流分析等程序分析技术，并且引入等值和别名分析以提高准确性，还通过源代码优化和设置多种不同级别的缓存，以提高检测速度和分析规模。本文将ABAZER系统实际应用于大型操作系统的源代码，实验结果表明，ABAZER具有较高的实用性和有效性。 缓冲区溢出是一种最为常见的软件安全缺陷类型，本文研究了针对缓冲区溢出的一种防御机制——地址空间随机化。本文描述了地址空间随机化在FreeBSD6.0中的设计和实现，并对其防护效果进行了理论评估和实际测试。As software scale augments day by day, software becomes more and more complicated. Various kinds of security bugs hidden in software have caused serious security problems and even great losses of resources. Software developers adopt many measures during software development in order to reduce the risk. As an important one of these measures, static code analysis has been used to find software security bugs. But the present static code analysis tools, especially those that are open source, can not achieve good complehensive effect on scale and accuracy. ABAZER, an automated bug analysis system given in this paper, adopts some effective methods to resolve the problem. This paper describes the design and implmentation of ABAZER in detail. ABAZER provides a language called BDL, which can be used by users to define various temporal logic security bugs. BDL adopts state machine to describe this kind of bugs. In order to define bugs more accurately, BDL language provides a kind of value-variable to support value analysis partly. ABAZER uses control flow analysis technique and some other program analysis techniques to analyze source code. Equivalence and alias analysis are supported in order to improve accuracy. To improve speed and scale, ABAZER implements several different-level caches and provides a new algorithm to optimize source code. We have applied ABAZER on real-world source code. One application is on the kernel of a secure operating system, and the result indicates that ABAZER is practical and effective. As buffer overflow is a popular kind of software security bug, we conduct study and experiment on address space randomization, an effect dynamic defense mechanism against buffer overflow attacks. This paper describes the design and implementation of the address space randomization in FreeBSD6.0, and the effectiveness evaluation of defense is also given

Value Equality Analysis in C Program API Conformance Validation

在实际中对C代码进行API一致性检验的过程中发现，API(application programming interface)规范大都涉及以数值为论域的时序性质与在静态分析过程中所能获取的以变量符号为占位符的独立语义之间存在分析上的缺口．在仔细考察c代码变量符号间等值关系的基础上，给出基于值等价类空间的等值分析方法．这种流相关的分析方法不仅可以在API一致性检验的过程中维护变量符号域和数值域之间的对应关系，而且由于能够屏蔽等值关系以外的其他信息，还可以为后继分析的优化提供有力的支持

一种增强的自主访问控制机制的设计和实现

自主访问控制是安全操作系统的基本安全机制之一,传统的文件保护位方式无法满足高安全等级操作系统对于自主访问控制机制的要求。对基于访问控制表的自主访问控制机制的设计和实现进行了研究。在此基础上提出并实现3种重要的增强和改进措施

Rapid parameter estimation for merging massive black hole binaries using continuous normalizing flows

Detecting the coalescences of massive black hole binaries (MBHBs) is one of the primary targets for space-based gravitational wave observatories such as laser interferometer space antenna, Taiji, and Tianqin. The fast and accurate parameter estimation of merging MBHBs is of great significance for the global fitting of all resolvable sources, as well as the astrophysical interpretation of gravitational wave signals. However, such analyses usually entail significant computational costs. To address these challenges, inspired by the latest progress in generative models, we explore the application of continuous normalizing flows (CNFs) on the parameter estimation of MBHBs. Specifically, we employ linear interpolation and trig interpolation methods to construct transport paths for training CNFs. Additionally, we creatively introduce a parameter transformation method based on the symmetry in the detector's response function. This transformation is integrated within CNFs, allowing us to train the model using a simplified dataset, and then perform parameter estimation on more general data, hence also acting as a crucial factor in improving the training speed. In conclusion, for the first time, within a comprehensive and reasonable parameter range, we have achieved a complete and unbiased 11-dimensional rapid inference for MBHBs in the presence of astrophysical confusion noise using CNFs. In the experiments based on simulated data, our model produces posterior distributions comparable to those obtained by nested sampling

新型空气悬浮式氧化风机的节能技术分析

本研究针对燃煤火电厂脱硫氧化风机，通过将罗茨式风机升级为新型的空气悬浮式风机，以提高氧化风机的运行效率和可靠性，降低能耗和噪声。结果表明空气悬浮式氧化风机采用的核心新技术包括永磁同步高速直联电机、无油空气悬浮轴承、单机单叶轮、内循环热交换冷却技术。无油空气悬浮轴承的工作原理是利用回转轴和轴承之间的相对运动形成流体动力场和浮扬力，使回转轴处于悬浮状态，无需润滑油，所以能量损耗极低，效率极高，能适用于 10 万转的大功率高转速机械。</jats:p

一种培养发菜细胞的方法

本发明公开了一种培养发菜细胞的方法,1.培养液的配制：将配制好的贮藏液加入水中的顺序是,硝酸钠、磷酸氢二钾、七水硫酸镁、二水氯化钙、九水硅酸钠、微量金属元素溶液PIV、土壤浸出液按比例配制；2.藻细胞匀浆的制备,首先将野生发菜丝状体用乙醇和蒸馏水洗涤,无菌培养液浸泡8-10h；其次是用玻璃匀浆器将丝状体匀浆破碎,匀浆液用于细胞培养；3.藻种无菌纯化；4.藻细胞培养；5.实时监控；6.收获；7.干燥；8.继续培养。本发明方法简单,操作方便,安全无污染,生长周期短,生产效率高,营养成分全面,营养含量高,广泛适用于城乡规模化生产培养