基于动力学与运动学的四轮全向移动机器人轨迹跟踪控制

建立了四轮全向移动机器人的运动学模型和动力学模型,并分析了四轮全向移动机器人执行器的机械特性。在此基础上,利用反馈控制设计了四轮全向移动机器人的运动学控制器,利用逆动力学补偿控制设计了四轮全向移动机器人的动力学控制器,实现了基于动力学与运动学的四轮全向移动机器人轨迹跟踪控制系统设计。最后,利用Matlab/Simulink完成了基于动力学与运动学的四轮全向移动机器人轨迹跟踪控制仿真实验,实验结果验证了该轨迹跟踪控制方法的有效性。     

PUBLIC SAFETY AND THE MORAL DILEMMA IN THE DEFENSE AGAINST TERROR

The economic theory of defense has traditionally described public safety as achieved through investments that deter adversaries. Deterrence is, however, ineffective and pre‐emptive defense is required when a population of intended victims confronts supreme‐value suicide terror. A moral dilemma then arises, since pre‐emption may impose collective punishment, while in the absence of pre‐emption the population of intended victims is exposed to acts of terror. We consider how a population of intended terror victims confronts the moral dilemma, and compare the threatened population's response with the public‐safety recommendations of external judges who are not personally affected by the threat of terror.     

Ridge regression analysis of the defence‐growth tradeoff in the United States

An examination of past analyses suggests that today's sailors may be less responsive to compensation changes than previous generations. Such a change could make recruiting and retaining high‐quality sailors more difficult. However, variation in researchers' decisions over time may simply have created the appearance of such a change. Our results suggest there is little variation in the pay elasticity over time. In contrast, the different reduced‐form models we use to measure this relationship can explain most of the variation in the literature. Therefore, the evidence suggests that while sailors may have changed over time, their response to compensation has not.     

THE ‘PRICE’ OF TERRORISM

Security measures are said to increase the price of terrorism. This price has not been hitherto defined in an economically meaningful way. This paper provides a precise definition by treating the terrorists’ resource endowment as a parcel of contingent claims to political influence with a price equal to the summed value of those contingent claims in potential states of the world. Equipped with this definition, an equilibrium model of the price of terrorism is deployed. Important insights are gained into the effect of terrorists’ risk aversion at the level of the price of terrorism in different states of the world and the theoretical conclusion is reached that higher security is associated with a lower price of terrorism rather than a higher price. The implications for policy are discussed.     

Minimizing Public Sector Corruption: The Economics of Crime,Identity Economics,and Money Laundering

Abstract

This paper offers a simple strategic framework to help governments identify various policy mechanisms to minimize public sector corruption. The paper offers a formal model that blends the economics of crime with identity economics and money laundering. It presents a partial equilibrium framework that focuses on a representative public official engaged in a mix of legal and illegal effort. The model introduces various levers a government might use to impact the costs and benefits of illegal effort. The ultimate goal is to help turn volatile vicious cycles of political instability, into steady virtuous cycles of stability, growth, and sustainable development.     

Corporate performance and military production in South Africa

With the end of the Cold War and apartheid, a process of demilitarisation and dramatic cuts in military spending has marked the transition to democracy in South Africa. Between 1989 and 1997 the South African defence budget was cut by more than 50% in real terms, with most of the cuts coming from the procurement budget, which was cut by nearly 70% in real terms during the same period. These cuts have had a significant impact on the country's defence industrial base. However, there has been surprisingly little research on the changes to defence companies that have taken place since the late 1980s. This paper makes a start at rectifying that deficiency by providing an analysis of the restructuring of the major defence‐dependent companies over the period 1988–97. It uses a number of financial ratios and other measures of corporate performance to compare their experience with non‐defence companies in the rest of the South African economy during the same period.     

Counter-terrorism in the Horn of Africa: New security frontiers,old Strategies

The US-led ‘war on terror’ dramatically changed America's security strategy towards Africa. But more fundamentally, it threw the Horn of Africa on the centre stage of global counter-terrorism. A double-edged blade, counter-terrorism has at once catalysed peace processes and intensified insecurity, with Islamic radicalism at the core of the regional storm. Governments utilised the threat of terrorism for political ends, defending old security paradigms that prioritised regime stability over human security. Africa integrated counter-terrorism into its emerging security agenda, but insufficient funds, operational constraints and poor coordination with international initiatives have hampered meaningful progress. Washington, laudably, launched a robust counter-terrorist campaign, but its high-handed military-heavy style put fragile democracies at risk while lapses in its overall policy risk triggering proxy wars. This essay examines the impact of counter-terrorism on security in the Horn of Africa. It argues for stronger coordination between national, regional and international initiatives to curb international terrorism.     

SPEED BUMP ON THE ROAD TO GLOBAL ZERO

The prospect of the United States continuing to reduce the size of its nuclear arsenal to “very low numbers” has raised questions in Japan and South Korea, where US extended deterrence guarantees are premised on the “nuclear umbrella.” In both countries, however, concerns focus less on numerical arsenal size than on the sufficiency of specific nuclear and non-nuclear capabilities to meet evolving threats and on the degree of broader US commitment to these alliances. This article assesses developments in US-Japan and US-South Korea relationships in response to the Obama administration's nuclear disarmament policies, focusing on how the evolutionary course of those relationships may in turn condition prospects for sustaining this US nuclear policy direction. The analysis finds that the challenges of deterrence credibility and allied reassurance are difficult and long-term, but also that US nuclear arsenal size is secondary to broader political, strategic, and military factors in meeting these challenges. The evaluation concludes that strong alliance relationships and strategic stability in East Asia can be maintained while the size of the US nuclear arsenal continues to decline, but also that deterioration of these relationships could imperil core US nuclear policy and nonproliferation objectives.     

LEARNING TO LIVE WITH A NUCLEAR IRAN

Claims that China is the only nuclear power currently expanding its arsenal fail to take into account the technical, historical, and bureaucratic realities that shaped China's nuclear posture and drive its ongoing modernization. China's strategic modernization is largely a process of deploying new delivery systems, not designing new nuclear warheads; the majority of its new missiles are conventionally armed. Today, China maintains the smallest operationally deployed nuclear force of any of the legally recognized nuclear weapon states, operates under a no-first-use pledge, and keeps its warheads off alert. The modernization of China's delivery systems is the culmination of a decades-long plan to acquire the same capabilities deployed by the other nuclear powers. U.S. concerns about this modernization focus too much on deterring a deliberate Chinese attack and ignore the risk that modernized U.S. and Chinese forces could interact in unexpected ways during a crisis, creating uncontrollable escalatory pressures. To manage this risk, Washington should assure Chinese leaders that it does not seek to deny China's deterrent, in exchange for some understanding that China will not seek numerical parity with U.S. nuclear forces.