An Error Rate Comparison of Power Domain Non-orthogonal Multiple Access and Sparse Code Multiple Access

Non-orthogonal Multiple Access (NOMA) has been envisioned as one of the key enabling techniques to fulfill the requirements of future wireless networks. The primary benefit of NOMA is higher spectrum efficiency compared to Orthogonal Multiple Access (OMA). This paper presents an error rate comparison of two distinct NOMA schemes, i.e., power domain NOMA (PD-NOMA) and Sparse Code Multiple Access (SCMA). In a typical PD-NOMA system, successive interference cancellation (SIC) is utilized at the receiver, which however may lead to error propagation. In comparison, message passing decoding is employed in SCMA. To attain the best error rate performance of PD-NOMA, we optimize the power allocation with the aid of pairwise error probability and then carry out the decoding using generalized sphere decoder (GSD). Our extensive simulation results show that SCMA system with “5×10” setting (i.e., ten users communicate over five subcarriers, each active over two subcarriers) achieves better uncoded BER and coded BER performance than both typical “1×2” and “2×4” PD-NOMA systems in uplink Rayleigh fading channel. Finally, the impacts of channel estimation error on SCMA , SIC and GSD based PD-NOMA and the complexity of multiuser detection schemes are also discussed

Performance of an internet data center refrigeration system using an evaporative cooler

The traditional refrigeration method of internet data center (IDC) is mostly air refrigeration, which has undesired cooling effect and high power consumption. This study addresses this problem and proposes an evaporative air cooler (EAC) suitable for IDC. Given the high specific heat capacity of water, the evaporative condensing coil and spray device are added to the evaporative cooler to enhance the heat transfer effect. Heat and mass transfer mathematical models are established to analyze the heat transfer performance. The mathematical model is used to simulate the profile of the heat and mass transfer coefficient of the EAC with the amount of spray water and air flow. The results show that when the air flow changes from 10 to 20 kg/s, the air equivalent heat transfer coefficient increases by about 41%. When the air flow rate is 20 kg/s and the spray water volume is 0.00124 kg/(mꞏs), the total heat transfer coefficient is increased by about 308% compared with the case without spray water

Effect of Laser Surface Structuring on Surface Wettability and Tribological Performance of Bulk Metallic Glass

Bulk metallic glasses (BMGs) have been extremely popular in recent decades, owing to their superior properties. However, how to improve the surface functions and durability of BMGs has always been a key engineering issue. In this work, a facile laser-based surface structuring technique was developed for modulation and control of the surface functionalities of Zr-based BMG. For this technique, a laser beam was first irradiated on the surface to create periodic surface structure, followed by heat treatment to control surface chemistry. Through experimental analyses, it was clearly shown that laser surface structuring turned the BMG surface superhydrophilic, and subsequent heat treatment turned the surface superhydrophobic. We confirmed that the combination of laser-induced periodic surface structure and modified surface chemistry contributed to the wettability transition. The laser-heat-treated surface also exhibited improved antifriction performance with the help of lubrication medium. This work provides a feasible method for surface modification of BMG, suggesting applications in the areas of medicine, biology and microelectronics

DESIGN AND ANALYSIS OF INERTIA VIBRATOR WITH ADJUSTABLE ECCENTRIC MASS

In order to make the exciting force adjustment of inertia vibrator during operation possible,and to meet the demand of particular vibrating machines,a kind of inertia vibrator is designed,it’s eccentric mass can be adjusted by pressure air. The design principal,structure design,analysis and calculation model is established. Furthermore,the relationship of centrifugal force to rotating speed,pressure,as well as the both,and the equations and curves are drawn and established. The research results could be guidance for design and production of institutes and factories

Therapeutic Effects of Kangzhi Syrup in a Guinea Pig Model of Ovalbumin-Induced Cough Variant Asthma

Purpose. This study aimed to investigate the possible effects and underlying mechanisms of Kangzhi syrup on ovalbumin- (OVA-) induced cough variant asthma (CVA) in guinea pigs. Methods. All 48 guinea pigs were randomly assigned to four experimental groups: normal, OVA model with or without Kangzhi syrup (OVA and OVA + KZ), and OVA with Dexamethasone (OVA + DM). After sensitizing the guinea pigs, a cough challenge was performed by the inhalation of capsaicin. The antitussive effect, inflammatory cells, cytokines in bronchoalveolar lavage fluid (BALF) and lung tissue, and morphological changes were examined. Results. Compared with model group, Kangzhi syrup effectively exerted an antitussive effect (p<0.0001) and reduced the pneumonic anaphylacticitis by inhibiting the infiltration of total inflammatory cells (p<0.0001) and reducing the percentage of eosinophil in BALF (p<0.0001). Moreover, evidence from morphological studies also demonstrated that Kangzhi syrup inhibited the infiltration of inflammatory cells and ameliorated the structure changes. NF-κB and TGF-β1 expression were attenuated in the OVA + KZ group versus the OVA group (p<0.0001). Additionally, a semiquantitative analysis of TGF-β1 expression also demonstrated that the Kangzhi syrup attenuated this profibrogenic growth factor (p<0.001). Conclusions. The results demonstrated that Kangzhi syrup exerted a considerable antitussive effect in CVA animal model, which depended on its marked impact on the anti-anaphylactic inflammation. Additionally, it could ameliorate the airway remodeling by inhibiting NF-κB and TGF-β1 signal pathway

MST1 Suppression Reduces Early Brain Injury by Inhibiting the NF-κB/MMP-9 Pathway after Subarachnoid Hemorrhage in Mice

Background. Mammalian sterile 20-like kinase 1 (MST1), the key component of the Hippo-YAP pathway, exhibits an important role in the pathophysiological process of various neurological disorders, including ischemic stroke and spinal cord injury. However, during subarachnoid hemorrhage, the involvement of MST1 in the pathophysiology of early brain injury remains unknown. Methods. We employed intravascular filament perforation to establish the subarachnoid hemorrhage (SAH) mouse model. The MST1 inhibitor XMU-MP-1 was intraperitoneally injected at 1 h after SAH, followed by daily injections. MST1 in vivo knockdown was performed 3 weeks prior to SAH via intracerebroventricular injection of adeno-associated virus (AAV) packaged with MST1 shRNA. The SAH grade, behavioral deficits, TUNEL staining, Evans blue dye extravasation and fluorescence, brain water content, protein and cytokine expressions by Western blotting, immunofluorescence, and proteome cytokine array were evaluated. Results. Following SAH, the phosphorylation level of MST1 was upregulated at 12 h, with a peak at 72 h after SAH. It was colocalized with the microglial marker Iba1. Both XMU-MP-1 and MST1 shRNA alleviated the neurological deficits, blood-brain barrier (BBB) disruption, brain edema, neuroinflammation, and white matter injury, which were induced by SAH in association with nuclear factor- (NF-) κB p65 and matrix metallopeptidase-9 (MMP-9) activation and downregulated endothelial junction protein expression. Conclusions. The current findings indicate that MST1 participates in SAH-induced BBB disruption and white matter fiber damage via the downstream NF-κB-MMP-9 signaling pathway. Therefore, MST1 antagonists may serve as a novel therapeutic target to prevent early brain injury in SAH patients

synthesisandcharacterizationofco3o4preparedfromatmosphericpressureacidleachliquorsofnickellateriteores

A chemical precipitation-thermal decomposition method was developed to synthesize Co_3O_4 nanoparticles using cobalt liquor obtained from the atmospheric pressure acid leaching process of nickel laterite ores. The effects of the precursor reaction temperature, the concentration of Co~(2+), and the calcination temperature on the specific surface area, morphology, and the electrochemical behavior of the obtained Co_3O_4 particles were investigated. The precursor basic cobaltous carbonate and cobaltosic oxide products were characterized and analyzed by Fourier transform infrared spectroscopy, thermogravimetric differential thermal analysis, X-ray diffraction, field-emission scanning electron microscopy, specific surface area analysis, and electrochemical analysis. The results indicate that the specific surface area of the Co_3O_4 particles with a diameter of 30 nm, which were obtained under the optimum conditions of a precursor reaction temperature of 30°C, 0.25 mol/L Co~(2+), and a calcination temperature of 350°C, was 48.89 m~2/g. Electrodes fabricated using Co_3O_4 nanoparticles exhibited good electrochemical properties, with a specific capacitance of 216.3 F/g at a scan rate of 100 mV/s

Toxic Mechanism and Biological Detoxification of Fumonisins

Food safety is related to the national economy and people&rsquo;s livelihood. Fumonisins are widely found in animal feed, feed raw materials, and human food. This can not only cause economic losses in animal husbandry but can also have carcinogenicity or teratogenicity and can be left in animal meat, eggs, and milk which may enter the human body and pose a serious threat to human health. Although there are many strategies to prevent fumonisins from entering the food chain, the traditional physical and chemical methods of mycotoxin removal have some disadvantages, such as an unstable effect, large nutrient loss, impact on the palatability of feed, and difficulty in mass production. As a safe, efficient, and environmentally friendly detoxification technology, biological detoxification attracts more and more attention from researchers and is gradually becoming an accepted technique. This work summarizes the toxic mechanism of fumonisins and highlights the advances of fumonisins in the detoxification of biological antioxidants, antagonistic microorganisms, and degradation mechanisms. Finally, the future challenges and focus of the biological control and degradation of fumonisins are discussed

A comprehensive characterization of virgin and recycled 316L powders during laser powder bed fusion

The primary constraints hindering the widespread adoption of laser powder bed fusion (LPBF) are expensive raw materials, internal defects, difficulty in controlling the quality and stability, and lack of consistency in the powder feedstock. The spatters induced by the violent interaction between the laser and powder can be deposited on the unmelted powder bed, and if not effectively separated by sieving, they would pose a significant detriment to the characteristics and consistency of the recycled powders. In this work, a systematic investigation of the evolution mechanism of 316L powders after 10 and 30 successive recycling in the LPBF process was presented. Firstly, the variation mechanism of particle size distribution and morphology of 316L powder and the generation mechanism of heterogeneous particles were studied. Then, changes in microstructure and hardness trends were characterized. Finally, we emphasized the changes of chemical composition, phase composition, magnetic properties, and the formation mechanism of oxide spots. The results show that the circulation had significant effects on the physical properties, phase transformation, mechanical properties, and magnetic properties of the 316L powders, but had minor effects on the chemical composition, surface and cross-sectional microstructure. In addition, a large number of oddly shaped, large-diameter spatters were identified in the recycled powders, which could not be separated effectively by sieving, and the formation mechanism of the spatters were elaborated. Based on the comprehensive high temperature oxidation thermodynamics and experimental results, it was concluded that the circular oxide spots on the spatter surface were a composite of multiple oxides of Mn and Si. Further, it was also shown that the ferrite content, XRD peak characteristics, and magnetic properties in the recycled powders were governed by the droplet solidification modes, which in turn is determined by the chemical composition and cooling rates. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)