1,618 research outputs found

    Storytelling Security: User-Intention Based Traffic Sanitization

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    Malicious software (malware) with decentralized communication infrastructure, such as peer-to-peer botnets, is difficult to detect. In this paper, we describe a traffic-sanitization method for identifying malware-triggered outbound connections from a personal computer. Our solution correlates user activities with the content of outbound traffic. Our key observation is that user-initiated outbound traffic typically has corresponding human inputs, i.e., keystroke or mouse clicks. Our analysis on the causal relations between user inputs and packet payload enables the efficient enforcement of the inter-packet dependency at the application level. We formalize our approach within the framework of protocol-state machine. We define new application-level traffic-sanitization policies that enforce the inter-packet dependencies. The dependency is derived from the transitions among protocol states that involve both user actions and network events. We refer to our methodology as storytelling security. We demonstrate a concrete realization of our methodology in the context of peer-to-peer file-sharing application, describe its use in blocking traffic of P2P bots on a host. We implement and evaluate our prototype in Windows operating system in both online and offline deployment settings. Our experimental evaluation along with case studies of real-world P2P applications demonstrates the feasibility of verifying the inter-packet dependencies. Our deep packet inspection incurs overhead on the outbound network flow. Our solution can also be used as an offline collect-and-analyze tool

    Investigation on efficiency improvement of a Kalina cycle by sliding condensation pressure method

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    Conventional Kalina cycle-based geothermal power plants are designed with a fixed working point determined by the local maximum ambient temperature during the year. A previous study indicated that the plant’s annual average thermal efficiency would be improved if the ammonia mass fraction of the Kalina cycle could be tuned to adapt to the ambient conditions. In this paper, another sliding condensation pressure method is investigated. A theoretical model is set up and then a numerical program is developed to analyze the cycle performance. The condensation pressure adjustment in accordance to the changing ambient temperature has been numerically demonstrated under various ammonia-water mixture concentrations. The results indicate that the Kalina cycle using sliding condensation pressure method can achieve much better annual average thermal efficiency than a conventional Kalina cycle through matching the cycle with the changing ambient temperature via controlling condensation pressure. Furthermore, the sliding condensation pressure method is compared with the composition tuning method. The results show that the annual average efficiency improvement of the sliding condensation pressure method is higher than that of the composition tuning method

    Corrections to holographic entanglement plateau

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    We investigate the robustness of the Araki-Lieb inequality in a two-dimensional (2D) conformal field theory (CFT) on torus. The inequality requires that ΔS=S(L)S(L)S()\Delta S=S(L)-|S(L-\ell)-S(\ell)| is nonnegative, where S(L)S(L) is the thermal entropy and S(L)S(L-\ell), S()S(\ell) are the entanglement entropies. Holographically there is an entanglement plateau in the BTZ black hole background, which means that there exists a critical length such that when c\ell \leq \ell_c the inequality saturates ΔS=0\Delta S=0. In thermal AdS background, the holographic entanglement entropy leads to ΔS=0\Delta S=0 for arbitrary \ell. We compute the next-to-leading order contributions to ΔS\Delta S in the large central charge CFT at both high and low temperatures. In both cases we show that ΔS\Delta S is strictly positive except for =0\ell = 0 or =L\ell = L. This turns out to be true for any 2D CFT. In calculating the single interval entanglement entropy in a thermal state, we develop new techniques to simplify the computation. At a high temperature, we ignore the finite size correction such that the problem is related to the entanglement entropy of double intervals on a complex plane. As a result, we show that the leading contribution from a primary module takes a universal form. At a low temperature, we show that the leading thermal correction to the entanglement entropy from a primary module does not take a universal form, depending on the details of the theory.Comment: 32 pages, 8 figures; V2, typos corrected, published versio

    Competition or Privatization: China’s Experience in SOE Reform

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    China is usually recognized in economic transition literature as a special case which achieved tremendous economic success simply through competitive market forces, without fundamental reforms in ownership system. That is, the Chinese model is generally regarded as an alternative to the privatization approach which was widely adopted in East Europe and Russia for economic and especially State Owned Enterprise (SOE) reform.This paper examines the characteristics of the Chinese model and identifies the exact nature of China’s SOE reform. For this purpose, this research adopted a comprehensive literature review as methodology, with particular focus on existing empirical studies on China’s SOE reform and Share Issuance Privatization (SIP). Specifically, first, this paper will describe the process and consequences of economic and SOE reforms in China. Second, it will identify the patterns and features of China’s privatization

    A regenerative supercritical-subcritical dual-loop organic Rankine cycle system for energy recovery from the waste heat of internal combustion engines

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    Organic Rankine cycle (ORC) system is considered as a promising technology for energy recovery from the waste heat rejected by internal combustion (IC) engines. However, such waste heat is normally contained in both coolant and exhaust gases at quite different temperatures. A single ORC system is usually unable to efficiently recover energy from both of these waste heat sources. A dual loop ORC system which essentially has two cascaded ORCs to recover energy from the engine’s exhaust gases and coolant separately has been proposed to address this challenge. In this way, the overall efficiency of energy recovery can be substantially improved. This paper examines a regenerative dual loop ORC system using a pair of environmentally friendly refrigerants, R1233zd and R1234yf, as working fluids, to recover energy from the waste heat of a compressed natural gas (CNG) engine. Unlike most previous studies focusing on the ORC system only, the present research analyses the ORC system and CNG engine together as an integrated system. As such, the ORC system is analysed on the basis of real data of waste heat sources of the CNG engine under various operational conditions. A numerical model is employed to analyse the performances of the proposed dual loop cycle with four pairs of working fluids. The effects of a regenerative heat exchanger and several other key operating parameters are also analysed and discussed in detail. The performance of the integrated engine-ORC system is then analysed under actual engine operating conditions which were measured beforehand. The performance of the proposed system under off-design conditions has also been analysed. The obtained results show that the proposed dual loop ORC system could achieve better performance than other ORC systems for similar applications

    Influence of male surgical sterilization on the copulatory behavior and reproduction of Brandt\u27s vole

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    The influence of sterilized male on the copulatory behavior and reproduction of Brandt′s vole was studied by using the method of surgical sterilization. Male surgical sterilization did not influence the copulatory behavior of Brandt\u27s vole. Mating times with intact mates and litter size of female Brandt′s voles in male sterilized groups decreased compared with the control groups. The results supported the hypothesis of competitively reproductive interference of sterilized males. Thus, sterilization can be a viable method to control voles

    Influence of increasing number of mating partners on mating behaviour and reproduction in Brandt’s voles

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    The influence of increasing number of mating partners on the copulatory behavior and reproduction in Brandt’s voles (Microtus brandti) was studied. Compared with the control group of 1 ♂ + 1 ♀, our results showed when increasing only female partners, the mating opportunity was increased in males while decreased in female in the treatment group of 1 ♂ + 2 ♀♀; the mating opportunity of male and female were both decreased significantly in the treatment group of 1 ♂ + 3 ♀♀. When increasing only male partners, male mating opportunity in treatment groups 2 ♂♂ + 1 ♀ and 3 ♂♂+ 1 ♀ decreased significantly while no change was significant in females in both treatment groups. When increasing the number of male and female partners simultaneously in the treatment group of 2 ♂♂ + 2 ♀♀, the mating opportunity for both males and females was decreased significantly. Comparing with the control, the mean litter size in all five-treatment groups lessened significantly and female pregnancy rate dropped significantly if they copulated less than five times. From these results, we have demonstrated a significant reproductive interference due to mate competition in Brandt’s voles and thus, competitively reproductive interference may be an important behavioral mechanism in regulating population density in this rodent species. However, due to possible laboratory artifacts, we still need further study, especially in the field, to validate our results
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