Fractal Metamaterial Absorber with Three-Order Oblique Cross Dipole Slot Structure and its Application for In-band RCS Reduction of Array Antennas

To miniaturize the perfect metamaterial absorber, a fractal three-order oblique cross dipole slot structure is proposed and investigated in this paper. The fractal perfect metamaterial absorber (FPMA) consists of two metallic layers separated by a lossy dielectric substrate. The top layer etched a three-order oblique fractal-shaped cross dipole slot set in a square patch and the bottom one is a solid metal. The parametric study is performed for providing practical design guidelines. A prototype with a thickness of 0.0106λ (λ is the wavelength at 3.18 GHz) of the FPMA was designed, fabricated, measured, and is loaded on a 1×10 guidewave slot array antennas to reduce the in-band radar cross section (RCS) based on their surface current distribution. Experiments are carried out to verify the simulation results, and the experimental results show that the absorption at normal incidence is above 90% from 3.17 to 3.22GHz, the size for the absorber is 0.1λ×0.1λ, the three-order FPMA is miniaturized 60% compared with the zero-order ones, and the array antennas significantly obtain the RCS reduction without the radiation deterioration

Experimental Analysis for Factors Affecting the Repeatability of Plastics Injection Molding Tests on the Self-developed Apparatus

To improve the repeatability of the injection molding test result, the affecting factors were investigated by means of experiments. Besides the traditional processing parameter, the factors of test conditions were also considered. In order to focus on the molding process rather than the molded part, the curve measurement of the melt pressure at the entrance to the nozzle was used as the output characteristic. Experiments for polypropylene (PP) showed that the injected volume was the key processing parameter. Within the test conditions, the injection number is the most important factor. According to the analysis the operating procedure was improved effectively. Doi: 10.12777/ijse.5.1.6-11 [How to cite this article: Huang, Y., Li, D., Liu, Y. (2013). Experimental Analysis for Factors Affecting the Repeatability of Plastics Injection Molding Tests on the Self-developed Apparatus. International Journal of Science and Engineering, 5(1),6-11. Doi: 10.12777/ijse.5.1.6-11

Thermo-mechanical controls of flat subduction: insights from numerical modeling

This study was supported by National Basic Research Program of China (2014CB440901), the Strategic Priority Research Program (B) of CAS (XDB18020104), National Science Foundation of China (41190073, 41372198 and 41304071), and NERC grant NE/J021822/1.Numerical experiments are used to investigate the thermo- mechanical controls for inducing flat subduction and why flat subduction is rare relative to normal/steep subduction. Our modeling results demonstrate that flat subduction is an end-member of a steady state subduction geometry and is characterized by a curved slab with a nearly-horizontal slab section. Intermediate cases between normal/steep and flat subduction appear to be transient in origin and evolve toward one of the stable end-members. Physical parameters inducing flat subduction can be classified into four categories: buoyancy of the subducting oceanic lithosphere (e.g., slab age, oceanic crustal thickness), viscous coupling between the overriding and downgoing plates (e.g., initial subduction angle), external kinematic conditions, and rheological properties of the subduction zone. On the basis of parameter sensitivity tests and the main characteristics of present-day flat subduction zones, positive buoyancy from either the young slab or the thickened oceanic crust are considered the primary controlling parameter. Our results show that the possibility of flat subduction is directly proportional to oceanic crustal thickness and inversely proportional to the slab age. Furthermore, oceanic crust must be thicker than 8 km to induce flat subduction, when the slab is older than 30 Ma with an initial subduction angle of ≥ 20°, and without absolute trenchward motion of the overriding plate. The lower the initial subduction angle or the thicker the overriding continental lithosphere, the more likelihood for flat subduction. The initial subduction angle is more influential for the development of flat subduction than the overriding lithospheric thickness, and a thick overriding lithosphere induces flat subduction only under the condition of an initial subduction angle of ≤ 25°, with a slab age of ≥ 30 Ma and without absolute trenchward motion of the overriding plate. However, when the initial subduction angle is increased to > 25°, no flat subduction is predicted. All the parameters are evaluated within the constraints of a mechanical framework in which the slab geometry is regarded as a result of a balance between the gravitational and hydrodynamic torque. Any factor that can sufficiently reduce gravitational torque or increase hydrodynamic torque will exert a strong effect on flat subduction development. Our results are consistent with the observations of modern flat subduction zones on Earth.PostprintPeer reviewe

The Impact of the Belt and Silk Road to the Development of the Countries along the Project

The world is advancing technologically and digitalizing. Therefore, to move with the trend and partake in the recovery that is taking place all over the world, the Belt and Silk Road Initiative was launched so as to link with economic globalization and immense Information Technology. It is aimed at enhancing global trade and this is to be done in an orderly way to see a smooth economic flow, since there will be adequate allocation of resources. It helps promote the economic prosperity of other countries, thus, encouraging trade routes and understanding from one country to the other. This in turn results in world development and world peace. With reference to the above assertion, the presentation serves to discuss the achievements that can be met, the demerit, and recommendations. Keywords: Belt Silk Road Initiative, Development, Countries DOI: 10.7176/JESD/11-16-05 Publication date:August 31st 202

Tourism and Its Impact on Economic Development

The relevant nature of tourism has been clearly found in this study. Tourism is recognized as the developmental factor for an economy. The study therefore chose to conduct the effect of tourism on economic development in Ghana. The study sought to analyze the relationship between tourism and infrastructural development in Ghana. It also examined the relationship between crime rate and tourism in Ghana and analyze the trend of tourism and economic growth in Ghana. The study also focused on examining the effect of tourism on the economic growth of Ghana and finally, analyzed the effectiveness of policy on tourism in Ghana. The study adopted quantitative approach through the use of secondary data from 1990 to 2019. Research analysis used for this study was the instrumental variable and correlation. The outcome of the study suggested that infrastructure development of the economy shows a positive relationship with tourism. It was also estimated in the study that when crime is high tourism tends to be low and vice versa. On the part of the estimation, natural resource was the variable used as the instrumental variable. The outcome from controlled variables such as international trade and exchange rate was found to be positively related to economic growth and development in Ghana. Also, instrumental variable estimation showed that tourism had a positive effect on the economic growth of Ghana. The outcome of the study revealed how the sector had reduced the unemployment rate in Ghana through the provision of both direct and indirect job for its people. The sector however is now coupled with challenges such policy issues and COVID 19 as revealed by players in the sector indicates the overreliance on government. Per the outcome of the study, it was recommended that long term policy should be put in place to ensure that successive government follow to prevent the distortion of the progress of the sector. It is recommended that infrastructure development and tourism should be investigated extensively by focusing on the effect of tourism on economic growth in Ghana. Keywords: Tourism, Economic Development DOI: 10.7176/JTHS/60-03 Publication date: March 31st 2022

Indosinian high-strain deformation for the Yunkaidashan tectonic belt, south China : Kinematics and 40Ar/39Ar geochronological constraints

Structural and 40Ar/39Ar data from the Yunkaidashan Belt document kinematic and tectonothermal characteristics of early Mesozoic Indosinian orogenesis in the southern part of the South China Block. The Yunkaidashan Belt is tectonically divided from east to west into the Wuchuang-Sihui shear zone, Xinyi-Gaozhou block, and the Fengshan-Qinxi shear zone. Indosinian structural elements ascribed to the Indosinian orogeny include D2 and D3 deformation. The early D2 phase is characterized by folding and thrusting with associated foliation and lineation development, related to NW-SE transpression under amphibolite- to greenschist-facies conditions. This event is heterogeneously overprinted by D3 deformation characterized by a gentle-dipping S-3 foliation, subhorizontally to shallowly plunging L3 lineation, some reactived-D2 folds and low-angle normal faults. The D3 fabrics suggest a sinistral transtensional regime under greenschist-facies metamorphism. The timing of the D2 and D3 events have been constrained to the early to middle Triassic (similar to 248-220 Ma) and late Triassic (similar to 220-200 Ma) respectively on the basis of 40Ar/39Ar geochronology and regional geological relations. The change from oblique thrusting (D2) to sinistral transtension (D3) may reflect oblique convergence and crustal thickening followed by relaxation of the overthickened crust. In combination with the regional relations from Xuefengshan to Yunkaidashan and on to Wuyishan, the early phase of the Indosinian orogeny constituted a large-scale positive flower structure and is related to the intracontinental convergence during the assembly of Pangea in which the less competent South China Orogen was squeezed between the more competent North China and Indosinian Blocks.Peer reviewe

An Examination of the Causal Relationship Between Tourism and Economic Growth in Ghana from 1987 to 2018

The growth of every nation is its ability to improve every sector of the economy that provides better outcomes through revenue mobilization and investment. With the Ghana’s attention shifted to tourism, it is imperative to identify how tourism could trigger growth in the country. Thus, the study sought to examine the causal relationship between tourism and economic growth of Ghana and its related challenges. The study adopted a mixed method approach in the collection and analysis of data. Both secondary and primary data were used in the analysis of the study. In analyzing the quantitative study, data on tourism and GDP from 1987 to 2018 were used. The study adopted the Johansen Cointegration test and the instrumental variable estimation to identify the causal relationship among the variables. The outcome of the study from the Johansen and Co-integration test instrumental variable showed that there is a unidirectional causal relationship between tourism receipt and GDP growth both in the short run and the long run and a positive significant effect of tourism on economic growth of Ghana. The result showed that government has been the major contributor to the sector. Also, the most challenging issue curtailing the sector was found to be the issue of the COVID 19 pandemic. As such, the study recommended that ensuring public-private partnership could improve the sector to ensure growth in the economy. Further extensive research is required to understand the effects of tourism on host communities. Keywords: Tourism, Gross Domestic Product (GDP), Economic Growth, Ghana, Tourism industry, Climate Change. DOI: 10.7176/JESD/11-20-04 Publication date:October 31st 202

Pre-gestational stress reduces the ratio of 5-HIAA to 5-HT and the expression of 5-HT1A receptor and serotonin transporter in the brain of foetal rat

<p>Abstract</p> <p>Background</p> <p>Many studies have found that stress before or during pregnancy is linked to an increased incidence of behavioural disorders in offspring. However, few studies have investigated hypothalamic-pituitary-adrenal (HPA) axis activity and the serotonergic system as a consequence of pregestational stress. In the present study, we investigated the effect of pre-gestational stress on HPA axis activity in maternal rats and their foetuses and examined whether changes in HPA axis activity of maternal rats produced functional changes in the serotonergic system in the brain of foetuses.</p> <p>Results</p> <p>We used the behavioural tests to assess the model of chronic unpredictable stress (CUS) in maternal rats. We found the activity in the open field and sucrose consumption was lower for rats with CUS than for the controls. Body weight but not brain weight was higher for control foetuses than those from the CUS group. Serum corticosterone and corticotrophin-releasing hormone levels were significantly higher for mothers with CUS before pregnancy and their foetuses than for the controls. Levels of 5-hydroxytryptamine (5-HT) were higher in the hippocampus and hypothalamus of foetuses in the CUS group than in the controls, and 5-hydroxyindoleacetic acid (5-HIAA) levels were lower in the hippocampus in foetuses in the CUS group than in the control group. Levels of 5-HIAA in the hypothalamus did not differ between foetuses in the CUS group and in the control group. The ratio of 5-HIAA to 5-HT was significantly lower for foetuses in the CUS group than in the control group. Levels of 5-HT1A receptor were significantly lower in the foetal hippocampus in the CUS group than in the control group, with no significant difference in the hypothalamus. The levels of serotonin transporter (SERT) were lower in both the foetal hippocampus and foetal hypothalamus in the CUS group than in the control group.</p> <p>Conclusions</p> <p>Our data demonstrate that pre-gestational stress alters HPA axis activity in maternal rats and their foetuses, which is associated with functional changes in 5-HT activity (5-HT, 5-HIAA and ratio of 5-HIAA to 5-HT), as well as the levels of the 5-HT1A receptor and SERT in the hippocampus and hypothalamus of foetuses.</p

DSAM-GN:Graph Network based on Dynamic Similarity Adjacency Matrices for Vehicle Re-identification

In recent years, vehicle re-identification (Re-ID) has gained increasing importance in various applications such as assisted driving systems, traffic flow management, and vehicle tracking, due to the growth of intelligent transportation systems. However, the presence of extraneous background information and occlusions can interfere with the learning of discriminative features, leading to significant variations in the same vehicle image across different scenarios. This paper proposes a method, named graph network based on dynamic similarity adjacency matrices (DSAM-GN), which incorporates a novel approach for constructing adjacency matrices to capture spatial relationships of local features and reduce background noise. Specifically, the proposed method divides the extracted vehicle features into different patches as nodes within the graph network. A spatial attention-based similarity adjacency matrix generation (SASAMG) module is employed to compute similarity matrices of nodes, and a dynamic erasure operation is applied to disconnect nodes with low similarity, resulting in similarity adjacency matrices. Finally, the nodes and similarity adjacency matrices are fed into graph networks to extract more discriminative features for vehicle Re-ID. Experimental results on public datasets VeRi-776 and VehicleID demonstrate the effectiveness of the proposed method compared with recent works.Comment: This paper has been accepted by the 20th Pacific Rim International Conference on Artificial Intelligence in 202

VRAC channel inhibition as a novel strategy for the treatment of ischemia-reperfusion injury

Ischemia-reperfusion injury is a serious clinical pathology involving multiple organs such as the heart and brain. The injury results from oxidative stress, inflammatory response and cell death triggered by restoring tissue blood flow after ischemia, leading to severe cell and tissue damage. In recent years, the volume-regulated anion channel (VRAC) has gained attention as an important membrane protein complex. VRAC plays a dual role in ischemia-reperfusion injury: on the one hand, activated VRAC promotes the release of intracellular chloride and glutamate, exacerbating cellular swelling and excitotoxicity, and on the other hand, the regulatory effect of VRAC may also provide protection to cardiomyocytes. This article reviews the pathophysiological mechanisms of ischemia-reperfusion injury, existing therapeutic strategies and their limitations, focuses on the molecular structure of VRAC, its activation mechanism, and its role in ischemia-reperfusion injury, and concludes with a discussion of the potential of targeted inhibition of VRAC as an emerging therapeutic strategy and the challenges it faces. A deeper understanding of the role of VRAC in ischemia-reperfusion injury is expected to provide new therapeutic ideas to improve patient prognosis