发动机冷却燃料超临界压力下做功潜力㶲分析

在高马赫数飞行下,超燃冲压发动机的燃料冷却量大于燃料燃烧量。为了降低燃料的冷却量以及实现燃料冷却量和燃烧量的匹配,采用分析法对超燃冲压发动机壁面燃料冷却工质在超临界压力下进行做功潜力分析。发动机壁面冷却燃料的特性决定其热量大小。根据发动机壁面温度分布、热流密度分布计算热量,建立稳定流动燃料工质的平衡方程。结果表明:在壁面最高温度为1200 K时,传入壁面的热量为562.4 k W,其中理论热量为541.3 k W;冷却燃料工质流量增加,最大输出功减小;燃料工质出口温度增加,输出功减小;燃料工质出口压力增加,输出功基本不变。     

可调喷油规律下柴油机性能随喷油提前角的影响

为获取可调喷油规律条件下,喷油提前角对柴油机性能的影响规律及成因机理。在实现可调喷油规律喷射的基础上,基于Fire软件建立了柴油机工作过程计算模型,并通过试验对模型中的主要参数进行了标定,进而利用模型分析了靴形喷油规律下柴油机性能随喷油提前角的变化。结果表明：随着增压时刻的滞后,喷油规律由矩形过渡到斜坡形再到靴形,实现了灵活可调的喷油规律。在靴形喷油规律条件下,存在一个最佳的喷油提前角,使柴油机的动力性和经济性均达到最优。同时,随着喷油提前角的增大,柴油机缸内压力、缸内温度以及放热率均逐渐升高,且到达各自最大值的时刻前移,而NOx排放量和碳烟排放量则分别呈现出增加和减小的趋势。     

试论科技进步与中国国际责任的现实担当

当代科技进步不仅影响着世界格局的变革,也深刻影响着国家的外交行为。随着中国经济实力和科技实力的快速发展,中国更为主动、自信地以大国身份融入国际社会,在几乎所有重要的全球性国际机制中都发挥着积极作用,遵守和履行相应的规则和义务,承担为国际社会提供公共产品以及维护正常合理的国际秩序等国际责任。但随着全球问题的不断增多,国际社会对中国承担更多国际责任的期待也在增多,有些西方国家甚至要求中国承担超出能力的国际责任。面对错综复杂的新形势,中国应该清醒认识自身的国际角色定位,在确保自身崛起的前提下,以科技实力和综合国力承担起力所能及的国际责任,为中国的和平发展提供更广泛的认同基础。     

基于灰色神经网络的装甲部队油料消耗预测

油料消耗量的精确预测直接影响装甲部队后勤保障能力的提升,而传统预测模型精度不高,应用范围也有一定的局限,难以满足信息化战争精确保障的需要。提出一种装甲部队油料消耗预测的组合模型,对历史油料消耗数据和油耗影响因素进行统计分析,求出各影响因素与油耗量的关联度作为权重系数;通过改进GM(1,1)模型预测某部队下一次军事行动的油耗量;用GM(1,1)模型的预测值、加权后的各影响因素值和油耗实际值训练网络,对下一次想定的军事行动油耗量进行预测。通过平均相对误差计算表明,组合预测模型比单一的GM(1,1)模型预测精度高,能够较好地指导部队进行下一步的油料供管工作。     

THE SUPPLY PRICE OF COMMITMENT: EVIDENCE FROM THE AIR FORCE ENLISTMENT BONUS PROGRAM

In fiscal year 1999, the US Air Force introduced a bonus program designed to encourage longer enlistment terms. This regime shift provides a unique opportunity to estimate the elasticity of labor supply at a new margin: the length of the employment contract. A $5000 bonus differential is estimated to increase the probability that a recruit will choose a 6‐year enlistment over a 4‐year enlistment by 30 percentage points. The program is found to be cost‐effective relative to other policies to increase man‐years.     

Police Corruption: Towards a Working Definition

According to the International Committee of the Red Cross (ICRC) publication Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law, all civilians (including child soldiers) lose their immunity from direct targeting ‘for so long as’ their actions amount to direct participation in hostilities. All civilians can, however, access the revolving door of protection and return to their civilian activities – complete with full immunity from direct targeting – provided the nature of their direct participation was spontaneous and disorganised. Once it can be ascertained that their participation in hostilities amounts to continuous combative functions, they relinquish their access to the revolving door of protection, and can be targeted at all times until they abandon their formal or functional membership of the belligerent group. This piece analyses how the revolving door phenomenon and the notion of continuous combative functions apply in instances where civilian child soldiers are directly participating in hostilities.     

REFASHIONING AUSTRALIA'S NUCLEAR BARGAIN?

This article explores the challenges that Australia faces in reconciling its commitments to nonproliferation and uranium exports during a time when the international nuclear nonproliferation regime is under major stress and the world uranium market is bullish. The “grand bargain” that has framed Australian participation in the nonproliferation regime and the nuclear fuel market since the 1970s was only tenable in an era of stagnant uranium demand and a stable nuclear balance. However, contemporary nuclear proliferation dynamics and the revival of interest in nuclear energy have accentuated the incompatibility between Australia's commitment to nonproliferation and the desire to profit from uranium exports. The contemporary international strategic environment, international nonproliferation regime, and nuclear energy market are characterized by developments that not only undermine the basis of Australia's grand bargain, but also present challenges and opportunities for the refashioning of Australian policy.     

US warfare in Somalia and the trade-off between casualty-aversion and civilian protection

This article examines the ways in which the two normative concerns of casualty-aversion and civilian protection influenced US military strategy in the particular context of the asymmetric conflict in Somalia in the early 1990s. The article critically evaluates US military operations through the prism of international humanitarian law and examines whether American forces started prioritizing casualty-aversion over the safeguarding of Somali civilians. Finally, by drawing on emerging moral guidelines (such as Michael Walzer's idea of ‘due care’), the article examines whether lower numbers of Somali civilian deaths could have been achieved if marginal increases to the risks faced by US soldiers had been accepted.     

The 1983 Nuclear Crisis – Lessons for Deterrence Theory and Practice

This article distills insights for the scholarship of deterrence by examining the 1983 nuclear crisis – the moment of maximum danger of the late Cold War. Important contributions notwithstanding, our understanding of this episode still has caveats, and a significant pool of theoretical lessons for strategic studies remain to be learned. Utilizing newly available sources, this article suggests an alternative interpretation of Soviet and US conduct. It argues that the then US deterrence strategy almost produced Soviet nuclear overreaction by nearly turning a NATO exercise into a prelude to a preventive Soviet attack. Building on historical findings, this article offers insights about a mechanism for deterrence effectiveness evaluation, recommends establishing a structure responsible for this endeavor, and introduces a new theoretical term to the strategic studies lexicon – a ‘culminating point of deterrence’.