3GPP-Like THz Channel Modeling for Indoor Office and Urban Microcellular Scenarios

Terahertz (THz) communication is envisioned as the possible technology for the sixth-generation (6G) communication system. THz channel propagation characteristics are the basis of designing and evaluating for THz communication system. In this paper, THz channel measurements at 100 GHz and 132 GHz are conducted in an indoor office scenario and an urban microcellular (UMi) scenario, respectively. Based on the measurement, the 3GPP-like channel parameters are extracted and analyzed. Moreover, the parameters models are available for the simulation of the channel impulse response by the geometry-based stochastic model (GBSM). Then, the comparisons between measurement-based parameter models and 3rd Generation Partnership Project (3GPP) channel models are investigated. It is observed that the case with path loss approaching free space exists in the NLoS scenario. Besides, the cluster number are 4 at LoS and 5 at NLoS in the indoor office and 4 at LoS and 3 at NLoS in the UMi, which are much less than 3GPP. The multipath component (MPC) in the THz channel distributes more simpler and more sparsely than the 3GPP millimeter wave (mm-wave) channel models. Furthermore, the ergodic capacity of mm-wave and THz are evaluated by the proposed THz GBSM implementation framework. The THz measurement model predicts the smallest capacity, indicating that high carrier frequency is limited to the single transmission mechanism of reflection and results in the reduction of cluster numbers and ergodic capacity. Generally, these results are helpful to understand and model the THz channel and apply the THz communication technique for 6G.Comment: 13 pages, 12 figures, 3 table

Association between Percentage of Neutrophils at Admission and in-Hospital Events in Patients ≥75 Years of Age with Acute Coronary Syndrome

Objective: The study aimed to evaluate the role of the neutrophil percentage (N%) at admission in predicting in-hospital major adverse cardiovascular events (MACE) in patients ≥75 years of age with acute coronary syndrome (ACS).Methods: A total of 1189 patients above 75 years of age with ACS hospitalized at the Second Xiangya Hospital between January 2013 and December 2017 were enrolled in this retrospective study. Receiver operator characteristic curve analysis was performed to calculate the optimal N% cut-off value for patient grouping. The in-hospital MACE consisted of acute left heart failure, stroke and any cause of death. Multivariable logistic analyses were used to assess the role of N% in predicting MACE in older patients with ACS.Results: The patients were divided into a high N% group (N% ≥74.17%, n=396) and low N% group (N%<74.17%, n=793) according to the N% cut-off value (N%=74.17%). The rate of MACEs during hospitalization was considerably higher in the high N% group than the low N% group (27.5% vs. 9.6%, P<0.001). After adjustment for other factors, high N% remained an independent risk factor for in-hospital MACE in older patients with ACS (odds ratio 1.779, 95% confidence interval 1.091–2.901, P=0.021).Conclusion: High N% at admission is an independent risk factor for in-hospital MACE in patients above 75 years of age with ACS

A fast framework construction and visualization method for particle-based fluid

© 2017, The Author(s). Fast and vivid fluid simulation and visualization is a challenge topic of study in recent years. Particle-based simulation method has been widely used in the art animation modeling and multimedia field. However, the requirements of huge numerical calculation and high quality of visualization usually result in a poor computing efficiency. In this work, in order to improve those issues, we present a fast framework for 3D fluid fast constructing and visualization which parallelizes the fluid algorithm based on the GPU computing framework and designs a direct surface visualization method for particle-based fluid data such as WCSPH, IISPH, and PCISPH. Considering on conventional polygonization or adaptive mesh methods may incur high computing costs and detail losses, an improved particle-based method is provided for real-time fluid surface rendering with the screen-space technology and the utilities of the modern graphics hardware to achieve the high performance rendering; meanwhile, it effectively protects fluid details. Furthermore, to realize the fast construction of scenes, an optimized design of parallel framework and interface is also discussed in our paper. Our method is convenient to enforce, and the results demonstrate a significant improvement in the performance and efficiency by being compared with several examples

A 16-channel reconfigurable OCDMA/DWDM system using continuous phase-shift SSFBGs

We demonstrate a reconfigurable 16-channel optical code-division multiple access (OCDMA)/dense wavelength division multiplexing (DWDM) system (4 OCDMA times 4 DWDM times 625 Mb/s) based on novel 31-chip, 40 Gchip/s quaternary phase coding gratings operating at a channel spacing of just 50 GHz. The system performance is studied for cases of both fixed and code-reconfigurable decoders. Error-free performance is achieved in both cases and for all 16 channels

Rapidly reconfigurable phase code generation and recognition using fiber Bragg gratings

We demonstrate a 16-chip, 40Gchip/s, reconfigurable fiber Bragg grating based quaternary phase en/decoder with a tuning time of &lt;2s between two different phase codes

Compact Local Structure-Preserving Algorithms for the Nonlinear Schrödinger Equation with Wave Operator

Combining the compact method with the structure-preserving algorithm, we propose a compact local energy-preserving scheme and a compact local momentum-preserving scheme for the nonlinear Schrödinger equation with wave operator (NSEW). The convergence rates of both schemes are Oh4+τ2. The discrete local conservative properties of the presented schemes are derived theoretically. Numerical experiments are carried out to demonstrate the convergence order and local conservation laws of the developed algorithms

Effects of chemical slurries on fixed abrasive chemical-mechanical polishing of optical silicon substrates

Chemical mechanical polishing (CMP) with fixed abrasive pad is an alternative machining method to loose abrasive lapping and partial polishing with traditional pad in the fabrication of optical silicon substrates. However, the effects of chemical slurry on the fixed abrasive polishing performance are not fully understood. In this work, a serial of CMP experiments with a fixed abrasive pad were carried out for optical silicon substrates using seven different chemical slurries i.e. de-ionized water, alkaline lubricant, colloidal silica, hydrogen peroxide (H2O2) and potassium hydroxide (KOH). The polishing performances of these slurries were evaluated and compared in terms of material removal rate (MRR), surface roughness and flatness of the polished silicon substrates. The polishing characteristics were also discussed to reveal material removal mechanism and silicon surface generation under different chemical environments.ASTAR (Agency for Sci., Tech. and Research, S’pore

Thermal Aging Properties of 500 kV AC and DC XLPE Cable Insulation Materials

Despite similar material composition and insulation application, the alternating current (AC) cross-linked polyethylene (XLPE) and direct current (DC) XLPE materials cannot replace each other due to different voltage forms. Herein, this work presents a systematical investigation into the effects of thermal aging on the material composition and properties of 500 kV-level commercial AC XLPE and DC XLPE materials. A higher content of antioxidants in the AC XLPE than in the DC XLPE was experimentally demonstrated via thermal analysis technologies, such as oxidation-induced time and oxidation-induced temperature. Retarded thermal oxidation and suppression of space charge effects were observed in thermally aged AC XLPE samples. On the other hand, the carbonyl index of DC XLPE dramatically rose when thermal aging was up to 168 h. The newly generated oxygen-containing groups provided deep trapping sites (~0.95 eV) for space charges and caused severe electric field distortion (120%) under &minus;50 kV/mm at room temperature in the aged DC XLPE samples. For the unaged XLPE materials, the positive space charge packets were attributed to the residue crosslinking byproducts, even after being treated in vacuum at 70 &deg;C for 24 h. Thus, it was reasoned that the DC XLPE material had a lower crosslinking degree to guarantee fewer crosslinking byproducts. This work offers a simple but accurate method for evaluating thermal oxidation resistance and space charge properties crucial for developing high-performance HVDC cable insulation materials