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The electrical power distribution network (PDN) is in the transition phase due to the integration of distributed energy resources (DERs). Therefore, an accurate and efficient modeling and simulation platform is the need of the hour to determine the dynamic behavior of the PDN. The recent computational hardware, such as GPU, FPGA, etc. enables new simulation paradigm and develop a more realistic platform in the form of system emulators. In this paper, an FPGA based electromagnetic transient (EMT) simulation framework for the PDN is presented. Conjugate-gradient (CG) based electrical network solver is implemented in the proposed framework, and a test case is analyzed for Jail substation of Guwahati city, India, to validate the simulation environment. It has been compared with the MATLAB based implementation for verifying its accuracy. The proposed EMT simulator is approximately 12.5 times faster as compared to its MATLAB implementation and exhibits good accuracy as well.

Hydraulic fracturing allows us to enhance the transport properties of a tight formation, but it remains difficult to predict the enhancement as a function of recorded acoustic events. With this in mind, we initiate pore-scale modeling of acoustic emission (AE) events based on percolation theory. The main objective is to predict the permeability enhancement by accounting for the number of AE events. We first develop a physically representative model of the intact pore space of the matrix of Tennessee sandstone at the core scale based on petrophysical measurements, which are porosity, permeability, and capillary pressure. A block-scale sample of the formation is then hydraulically fractured, where piezoelectric sensors record the events generated during stimulation. We predict the permeability enhancement of the formation at the core scale by accounting for the number of AE events per unit volume. Independent petrophysical measurements corroborate the predicted results based on percolation theory. The proposed model has major implications for characterizing the transport properties of the stimulated reservoir volume.

Aim To assess left ventricular (LV) function in HIV patients by two-dimensional (2D) echocardiography to determine the pattern of myocardial dysfunction, and any correlation between cardiac dysfunction and severity of HIV infection. Background Human immunodeficiency virus (HIV) infection may cause various cardiac dysfunctions in humans even in the asymptomatic state and its timely detection may have prognostic value. Materials and methods One hundred treatment naive, asymptomatic HIV cases were subjected to trans-thoracic echocardiographic (2D, M-mode, pulse-wave, continuous-wave and colour Doppler) assessment by a single blinded cardiologist. Results Twenty-nine (29%) of 100 patients (mean age: 36.8 years; male: 54%) had echocardiographic abnormalities. Grade 1 diastolic dysfunction was present in 20, reduced fractional shortening in 12, reduced ejection fraction ( Cases having diastolic dysfunction had significantly different CD4 counts, haemoglobin level and erythrocyte sedimentation rate (ESR) values than the cases without cardiac dysfunction. CD4 counts were significantly negatively correlated with deceleration time (r = −0.2622, P Conclusions Twenty-nine (29%) HIV cases in relatively advanced clinical stage had cardiac dysfunction on echocardiography without overt cardiac manifestations. The CD4 cell counts significantly correlated with the presence of diastolic dysfunction.

Background Vertebrobasilar insufficiency resulting from embolism, atherosclerosis, or arterial dissection has long been a challenge for successful management and outcomes. The main treatment options include medical therapy, angioplasty and stenting, and surgical revascularization. Unlike cardiac or peripheral vascular revascularization, large randomized trials with cerebrorevascularization have not revealed favorable outcomes. In patients who have failed maximal medical therapy, and having persistent debilitating symptomology, cerebral revascularization may still be a viable option. Methods We report 3 patients who presented with symptoms of vertebrobasilar ischemia. The diagnosis was verified by computerized tomographic arteriography and digital subtraction angiography. Results These patients subsequently underwent revascularization with a radial artery graft. We also present a comprehensive review of the literature of treatment for vertebrobasilar insufficiency. Conclusions Surgical revascularization should be considered in the posterior circulation in the rare subset of patients with VBI, who remain symptomatic despite having a protracted course of maximal medical therapy with large- and medium-sized vessel occlusions and poor collateral circulation.

Aneurysmal subarachnoid hemorrhage (SAH) remains an important health issue in the United States. Despite recent improvements in the diagnosis and treatment of cerebral aneurysms, the mortality rate following aneurysm rupture. In those patients who survive, up to 50% are left severely disabled. The goal of preventing the hemorrhage or re-hemorrhage can only be achieved by successfully excluding the aneurysm from the circulation. This article is a comprehensive review by contemporary vascular neurosurgeons and interventional neuroradiolgists on the modern management of cerebral aneurysms.

Wet-process enables flexible, large area-size organic devices to be fabricated cost-effectively via roll-to-roll manufacturing. However, wet-processed devices often show comparatively poor performance due to the lack of solution-process feasible functional materials that exhibit robust mechanical properties. We demonstrate here a cross-linkable material, 3,6-bis(4-vinylphenyl)-9-ethylcarbazole (VPEC), to facilitate the injection of hole and meanwhile effectively confine electron to realize, for examples, high efficiency organic light-emitting diodes, especially at high luminance. The VPEC shows a hole mobility of 1 10

Bends are frequently encountered in microdevices and therefore a fundamental understanding of flow through them is important. In this paper, we have used the lattice Boltzmann method to study flow of a gas through a microchannel with a single 90° bend. The computations are two-dimensional, isothermal, and for the Reynolds and Knudsen numbers typically observed. We find that the pressure drop in segments of equal lengths before and after the bend is different, and a recirculatory motion is seen near the bend even when the flow Reynolds number is less than unity. The velocity and pressure distribution between the bend and straight microchannels is almost identical at large Knudsen numbers, indicating that the flow does not feel the presence of the bend in such cases. This is attributed to rarefaction of the gas which hinders transfer of information across the flow.

The dissociative chemisorption of Cl2 on Si(1 1 4) was studied at room temperature using scanning tunneling microscopy. Filled and empty state imaging revealed a multitude of possible adsorption configurations with adsorption preferring rebonded atom and dimer sites over tetramer sites. The dissociation and subsequent adsorption processes were sufficiently exothermic that Cl could interrogate the potential energy landscape and find local energy minima. Annealing revealed configurations that preserved the strongest π-bonds of the (1 1 4) reconstruction.

In this paper we provide solution of the Navier–Stokes equations for gaseous slip flow in long microchannels with a second-order accurate slip boundary condition at the walls. The obtained solution is general enough to allow evaluation of various slip models proposed in the literature. We compare our solution against the first-order accurate slip boundary condition and show that the solution has a weak dependence on Reynolds number, which was neglected in the earlier theory. It is emphasized that first-order slip models do not predict the “Knudsen paradox” (appearance of a minima in normalized volume flux at Knudsen number approximately unity), or a change in curvature of centerline pressure at Knudsen numbers of 0.16. A comparison with Boltzmann’s solution suggests that the derived solution agrees reasonably well up to Knudsen number approximately 5, which shows that the validity of Navier–Stokes to rarefied gases can possibly be increased by using a high order slip boundary condition and proper choice of the slip coefficients. This result is significant from the perspective of numerical simulations of rarefied gases.

Cryptococcal spinal arachnoiditis occurs in patients with meningitis and usually when they are immunocompromised. Spinal symptoms in cryptococcosis are rare and a very exceptional entity in the immunocompetent population. We present a young immunocompetent male who developed progressively increasing paraparesis due to primary cryptococcal arachnoiditis, who showed significant improvement after antifungal therapy. Although extremely rare, spinal arachnoiditis in an immunocompetent individual can be caused due to cryptococcus, as in our case. This case illustrates and emphasizes the necessity for an exhaustive and complete investigation, with a high index of suspicion for fungal etiology in patients presenting with spinal arachnoiditis or other disabling, progressive spinal cord syndromes of unknown etiology. Awareness of this presentation is necessary to avoid delay in diagnosis and management of this potentially curable condition.

Halogen molecules dissociatively chemisorb on Si(1 0 0)-(2 × 1), and the bonding structures that they adopt can be elucidated with scanning tunneling microscopy. Of the Cl, Br, and I group, Cl has the highest single atom diffusion barrier, and both single and paired adatoms are observed at 295 K. The barrier is smaller for Br, and the adatoms can interrogate the surface until they form pairs, which are then immobile, or are trapped at C-type defects. The barrier is smallest for I, allowing the formation of pairs and trapped states, but the pairs are mobile at ambient temperature. Their motion is thermally activated, the events are random, and the diffusivities along and across the dimer row are ∼0.42 and ∼0.17 A 2 /s at 295 K. The respective energy barriers for pairwise diffusion are ∼0.76 and ∼0.82 eV, assuming an attempt frequency of 10 12 s −1 . Studies over long times reveal that pairwise diffusion at low coverage is ultimately quenched by the increasing density of C-type defects, i.e. the increasing amounts of dissociated H 2 O.

An optimization technique has been proposed to determine Hansen solubility parameters (HSP) and radius of interaction ( R ) of PLA and PGA; objective function to be minimized being radius of interaction ( R ), and the constraints being that the solvents should be within and nonsolvents outside the interaction sphere. The proposed method has been validated and found to be most reliable. The values of HSP ( δ d , δ p , δ h ) and R for PLA have been obtained as ((18.50, 9.70, 6.00) and 10.50) (J/cc) 0.5 at 25 °C; and those of PGA as ((17.70, 6.21, 12.50) and 1.92) (J/cc) 0.5 at 80 °C. For formulating the nonlinear inequality constraints known HSP data for 20 solvents and seven nonsolvents have been used for PLA at 25 °C; similarly HSP data for three newly found solvents (phenol, m -cresol and 4-chlorophenol), and five nonsolvents have been used for PGA at 80 °C. Established methods have been used for comparison. HSP and R have been directly compared using the 3D intrinsic viscosity and classical methods. Indirectly the total solubility parameter δ has been compared with the values obtained from the intrinsic viscosity 1D approach and group contribution method using Fedors and van Krevelen correlations. The 1D approach has led to an empirical correlation for intrinsic viscosities of PLA and PGA.

The United Nations (UN) is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace. The UN was founded in 1945 after World War II to replace the League of Nations, to stop wars between countries, and to provide a platform for dialogue. It contains multiple subsidiary organizations to carry out its missions.There are currently 193 member states, including every internationally recognized sovereign state in the world but the Vatican City. From its offices around the world, the UN and its specialized agencies decide on substantive and administrative issues in regular meetings held throughout the year. The organization has six principal organs: the General Assembly (the main deliberative assembly); the Security Council (for deciding certain resolutions for peace and security); the Economic and Social Council (for assisting in promoting international economic and social cooperation and development); the Secretariat (for providing studies, information, and facilities needed by the UN); the International Court of Justice (the primary judicial organ); and the United Nations Trusteeship Council (which is currently inactive). Other prominent UN System agencies include the World Health Organization (WHO), the World Food Program (WFP) and United Nations Children's Fund (UNICEF). One of the primary purposes of the United Nations is the maintenance of international peace and security. Since its creation, the UN has often been called upon to prevent disputes from escalating into war, to persuade opposing parties to use the conference table rather than force of arms, or to help restore peace when armed conflict does break out. Over the decades, the UN has helped to end numerous conflicts, often through actions of the Security Council — the primary organ for dealing with issues of international peace and security.The Security Council, the General Assembly and the Secretary-General all play major, complementary roles in fostering peace and security. . United Nations activities cover the principal areas of conflict prevention, peacemaking, peacekeeping, enforcement and peace building.