Note on ingoing coordinates for binary black holes

In a previous paper, a binary black hole four-metric was presented in a post-Newtonian corotating coordinate system valid only up to the holes' apparent horizons. In this paper, I define an ingoing coordinate transformation that extends this corotating coordinate system through the holes' horizons and into their interiors. The motivation for using ingoing coordinates is that numerical simulations of black holes require the computational grid to extend inside the horizons. The coordinate transformation presented here makes the binary black hole four-metric suitable as a source of initial data for numerical simulations

Impinging Jet Resonant Modes at Mach 1.5

High speed impinging jets have been the focus of several studies owing to their practical application and resonance dominated flow-field. The current study focuses on the identification and visualization of the resonant modes at certain critical impingement heights for a Mach 1.5 normally impinging jet. These modes are associated with high amplitude, discrete peaks in the power spectra and can be identified as having either axisymmetric or azimuthal modes. Their visualization is accomplished through phase-locked Schlieren imaging and fast-response pressure sensitive paint (PC-PSP) applied to the ground plane.Comment: videos and figures are attache

On Amplify-and-Forward Relaying Over Hyper-Rayleigh Fading Channels

Relayed transmission holds promise for the next generation of wireless communication systems due to the performance gains it can provide over non-cooperative systems. Recently hyper-Rayleigh fading, which represents fading conditions more severe than Rayleigh fading, has received attention in the context of many practical communication scenarios. Though power allocation for Amplify-and-Forward (AF) relaying networks has been studied in the literature, a theoretical analysis of the power allocation problem for hyper-Rayleigh fading channels is a novel contribution of this work. We develop an optimal power allocation (OPA) strategy for a dual-hop AF relaying network in which the relay-destination link experiences hyper-Rayleigh fading. A new closed-form expression for the average signal-to-noise ratio (SNR) at destination is derived and it is shown to provide a new upper-bound on the average SNR at destination, which outperforms a previously proposed upper-bound based on the well-known harmonic-geometric mean inequality. An OPA across the source and relay nodes, subject to a sum-power constraint, is proposed and it is shown to provide measurable performance gains in average SNR and SNR outage at the destination relative to the case of equal power allocation

Hubungan antara Leader Member Exchange dan Psychological Capital pada Perawat Rumah Sakit Jiwa

Rumah sakit dapat memberikan pelayanan yang maksimal apabila kondisi psikologis perawat positif. Psychological capital adalah sikap positif dalam diri perawat yang dikarakteristikan dengan hope, self-efficacy, resiliency, dan optimism. Pemimpin yang menerapkan leader member exchange akan memiliki interaksi yang positif dengan anggotanya. Penelitian ini bertujuan untuk mengetahui hubungan antara leader member exchange dengan pychological capital pada perawat rumah sakit jiwa. Populasi penelitian ini adalah perawat RSJD Dr. Amino Gondohutomo. Sampel penelitian sebanyak 70 perawat yang dipilih menggunakan teknik cluster random sampling. Pengumpulan data menggunakan dua buah skala yaitu skala psychological capital (42 aitem valid, α = .960) dan skala leader member exchange (26 aitem valid, α = .919). Hasil penelitian menunjukkan koefisien korelasi (rxy) = .800 dengan nilai p = .000 (p < .001). Hasil tersebut menunjukkan bahwa hipotesis yang diajukan peneliti terbukti, yaitu terdapat hubungan positif yang signifikan antara variabel leader member exchange dengan psychological capital. Semakin positif leader member exchange maka semakin tinggi psychological capital. Sumbangan efektif yang diberikan pada penelitian ini sebesar 64% dan 36% dipengaruhi oleh faktor lain yang tidak diukur dalam penelitian

Developing a Framework to Implement Public Key Infrastructure Enabled Security in XML Documents

This paper concentrates on proposing a framework to implement the PKI enables security in XML documents, by defining a common framework and processing rules that can be shared across applications using common tools, avoiding the need for extensive customization of applications to add security. The Framework reuses the concepts, algorithms and core technologies of legacy security systems while introducing changes necessary to support extensible integration with XML. This allows interoperability with a wide range of existing infrastructures and across deployments. Currently no strict security models and mechanisms are available that can provide specification and enforcement of security policies for XML documents. Such models are crucial in order to facilitate a secure dissemination of XML documents, containing information of different sensitivity levels, among (possibly large) user communities

Optimal Compression and Transmission Rate Control for Node-Lifetime Maximization

We consider a system that is composed of an energy constrained sensor node and a sink node, and devise optimal data compression and transmission policies with an objective to prolong the lifetime of the sensor node. While applying compression before transmission reduces the energy consumption of transmitting the sensed data, blindly applying too much compression may even exceed the cost of transmitting raw data, thereby losing its purpose. Hence, it is important to investigate the trade-off between data compression and transmission energy costs. In this paper, we study the joint optimal compression-transmission design in three scenarios which differ in terms of the available channel information at the sensor node, and cover a wide range of practical situations. We formulate and solve joint optimization problems aiming to maximize the lifetime of the sensor node whilst satisfying specific delay and bit error rate (BER) constraints. Our results show that a jointly optimized compression-transmission policy achieves significantly longer lifetime (90% to 2000%) as compared to optimizing transmission only without compression. Importantly, this performance advantage is most profound when the delay constraint is stringent, which demonstrates its suitability for low latency communication in future wireless networks.Comment: accepted for publication in IEEE Transactions on Wireless Communicaiton

FOREIGN AID, GROWTH, POLICY AND REFORM

Whether good macroeconomic policy facilitates aid effectiveness in generating growth is a highly debated topic. In this paper we investigate if economic reform has a favorable effect on the aid-growth relation—specifically, if reform enhances the effect of aid on growth. In doing so, we also construct a new policy index and examine the robustness of the Burnside and Dollar (2000) ‘policy view'. The results indicate that although our new policy index and reform are both growth enhancing, they do not increase aid-effectiveness and aid seem to play no positive role in the picture.