浅谈移动Ad Hoc网络按需路由协议中的篡改攻击问题

由于移动Ad Hoc网络具有动态变化的特性以及自组织和多跳性的特点,更容易遭受多种恶意攻击。其中篡改攻击就是最严重的一种攻击。本文详细剖析了篡改攻击问题,针对此问题提出了一种简洁的解决方案。此方案利用路由发现过程中中间结点计算的MAC值以及邻居维护机制提供的认证信息一起能够很好的抵抗篡改攻击,提高了路由协议的安全性。     

Do shocks have permanent or transitory effects on tourist inflow? An application of stationarity test with structural breaks: evidence reexamined for Gilgit-Baltistan,Pakistan

ABSTRACT

Do shocks affect tourist inflows permanently or temporarily? To examine this question, we consider a region in Northern Pakistan, Gilgit-Baltistan, known for its natural and scenic beauty and with a history of huge tourist inflows, both domestic and international. The tourist arrivals from significant source markets are investigated using univariate and Lagrange Multiplier (LM) unit root tests with two structural breaks to examine if shocks to the time path of visitors’ inflow are permanent or transitory. According to the results, the univariate and LM unit root test with two breaks reject the unit root null for all major source markets. The findings suggest transistory effects rather than permanent effects of shocks on the growth path of tourist arrivals to Gilgit-Baltistan. This result further predicts the sustainability of the tourism sector in the region in the long run.     

Second moments in speculative attack models: panel evidence

The paper tests two popular asset based models of speculative attacks and in particular, their emphasis on the second moments of monetary aggregates. Analyzing monthly panels of appropriate countries in three regions, it finds evidence for the importance of money/reserve ratios predicted by both models, as well as the variance of the ratio of M2 to reserves.     

Interactive unawareness

The standard state-spaces of asymmetric information preclude non-trivial forms of unawareness (Modica and Rustichini (Theory Decision 37 (1994) 107–124); Dekel, Lipman and Rustichini (Econometrica 66 (1998) 159–173)). We introduce a generalized state-space model that allows for non-trivial unawareness among several individuals, and which satisfies strong properties of knowledge as well as all the desiderata on unawareness proposed this far in the literature.     

A simple test of the effect of interest rate defense

High interest rates to defend the exchange rate signal that a government is committed to fixed exchange rates, but may also signal weak fundamentals. We test the effectiveness of the interest rate defense by disaggregating into the effects on future interest rates differentials, expectations of future exchange rates, and risk premia. While much previous empirical work has been inconclusive due to offsetting effects, tests that “disaggregate” the effects provide significant information. Raising overnight interest rates strengthens the exchange rate over the short-term, but also leads to an expected depreciation at a horizon of a year and longer and an increase in the risk premium, consistent with the argument that it also signals weak fundamentals. J. Japanese Int. Economies 20 (4) (2006) 612–636.     

The Economic Impacts of a Terrorist Attack on the Downtown Los Angeles Financial District

Abstract

This paper summarizes a study on the economic impacts of a radiological bomb attack on a major office building in downtown Los Angeles financial district. A radiological bomb will generate effects within an extensive radiation plume that is divided into two zones with varying evacuation times: an Inner Zone with a 1-year evacuation and an Outer Zone with only a 1-month evacuation time. An up-to-date version of a Garin–Lowry-style regional input–output model called SCPM 2005 is employed to simulate household and firm relocation in three scenarios. The impact analysis focuses on business interruption effects only.

Impact économique d'une attaque terroriste sur le quartier financier du centre de Los Angeles

Résumé Cet article concerne une étude sur l'impact économique d'une attaque par bombe radiologique sur un immeuble de bureaux dans le quartier financier du centre de Los Angeles. Une bombe radiologique engendre des effets au cæur d'un vaste panache radioactif, qui est divisé en deux zones possédant des durées d’évacuation différentes. La durée d’évacuation est d'un an dans la zone interne, et d'un mois seulement dans la zone externe. Trois scénarios de délocalisation de ménages et d'entreprises sont simulés grâce à l'utilisation d'une version actuelle d'un modèle régional intrants-extrants de type Garin–Lowry, appelé SCPM 2005. L'analyse de l'impact se concentre uniquement sur les effets de l'interruption du commerce.

El impacto económico de un ataque terrorista en el distrito financiero del centro de Los Ángeles

Résumén?Este trabajo resume un estudio sobre el impacto económico de un ataque de bomba radiológico en un importante edificio de oficinas en el distrito financiero del centro de Los Ángeles. Una bomba radiológica generará efectos dentro de una pluma radioactiva extensiva, dividida en dos zonas con diferentes tiempos de evacuación: una zona interna con un período de evacuación de un año y una zona externa con un período de evacuación de sólo un mes. Se emplea una versión actualizada de un modelo estilo Garin–Lowry, de entrada-salida regional llamado SCPM 2005, para simular la relocalización de viviendas y firmas en tres escenarios. El análisis del impacto sólo se enfoca en los efectos de la interrupción del

     

我国防范国际游资发动投机性冲击的对策

在当前特殊的国际背景下,我国必须密切关注国际游资的流动,防范国际游资发起投机性冲击。本文在界定国际游资定义的基础上,分析了国际游资对一国经济和世界经济的影响,探讨了国际游资发动投机性冲击的典型策略,总结了投机性冲击的特点,提出了我国防范国际游资发动投机性冲击的具体对策。     

Speculative residential developers and foreign retirees’ market segment in Malaysia

Over the last decade in particular, there has been a steady stream of foreign retirees, and more recently foreign high net worth individuals, who have joined Malaysia's My Second Home (MM2H) Programme which provides them with long-stay period visas. This opened up a new but small market segment for residential developers. A study was conducted to determine how the developers accommodate the MM2H participants by using the 4Ps framework. Data was collected using the mixed method of postal questionnaire survey and follow-up interviews. Customisation for the MM2H residential segment was generally limited to promotion of new dwellings. Total customisation in terms of product, price, place and promotion was found to be highly risky. Another ‘P’ for people cannot be excluded from 4Ps framework as speculative developers associate different nationalities with different house purchasing tendencies.     

The role of a large trader in a dynamic currency attack model

This paper studies the role of a large trader in a dynamic currency attack model based on Abreu and Brunnermeier (2003), who study stock market bubbles and crashes in a dynamic model with a continuum of rational small traders. We introduce a large trader into their model and apply it to currency attacks. In an attack against a fixed exchange rate regime with a gradually overvalued currency, traders lack common knowledge about the time when the overvaluation starts and need to coordinate to break a peg. Both the inability of traders to synchronize their attack and their incentive to time the collapse of the regime lead to the persistent overvaluation of the currency. We find that the presence of a large trader with perfect information induces small traders to attack sooner and leads to an accelerated collapse of the regime. But the presence of a large trader with noisy information may delay the collapse of the regime ex post. Moreover, a large trader with precise information tends to be at the rear of an attack. With noisy information, he could attack earlier or later than small traders. In both cases, the large trader affects market dynamics of the attack substantially.     

A model of currency crises with heterogeneous market beliefs

This paper shows that the approach followed by Tamborini (2015) in analyzing and interpreting the euro area public debt crisis, based on the role played by agents characterized by heterogeneous market beliefs, can be applied also to the case of currency crises. By doing so, rather than considering the private sector as an atomistic player endowed with perfect information, and by considering a central bank that optimizes the amount of unsterilized inflow of foreign reserves in a Mundell-Fleming type speculative attack model, allows to explain the interest rates convex non-linearity that characterized, for example, a country like Italy during the 1992–93 EMS crisis.