Unit Element Research Articles

Investigation of boron distribution and material migration on the W7-X divertor by picosecond LIBS

One set of horizontal target elements of the Test Divertor Units (TDU), retrieved from the Wendelstein 7-X (W7-X) vessel after the end of second divertor Operation Phase (OP1.2B) in Hydrogen (H), were investigated by picosecond Laser-Induced Breakdown Spectroscopy (ps-LIBS). The Boron (B) distribution, H pattern and the material erosion/deposition pattern on these target elements were analyzed with high depth resolution and mapped in the poloidal direction of W7-X. From the spectroscopic analysis, B, H, Carbon (C) and Molybdenum (Mo) were clearly identified. A non-uniformly distributed B pattern on these divertor target elements was determined by the combination of B layer deposition during the three boronizations and W7-X plasma operation with multiple erosion and deposition steps of B. Like the TDU, the analyzed target elements are made of fine grain graphite, but have two marker layers which allow us to determine the material migration via the ps-LIBS technique. Two net erosion zones including one main erosion zone with a peak erosion depth of 6.5 μm and one weak erosion with a peak erosion of 1.3 μm were determined. Between two net erosion zones, a net deposition zone with width of 135 mm and a thickness up to 3.5 μm at the peak deposition location was determined by the ps-LIBS technique. The B distributions are correlated with the erosion/deposition pattern and the operational time in standard magnetic configuration of W7-X in the phases after the boronizations. The thickness of the containing B layer on these target elements also correlates with the erosion/deposition depth, in which the thickness of the containing B layer varies spatially in poloidal direction between 0.1 μm and 6 μm. Complementary, Focused Ion Beam combined with Scanning Electron Microscopy (FIB-SEM) was employed also to verify and investigate the deposition layer thicknesses at typical net erosion and net deposition zones as well as to identify the three boronizations in depth.

On the Nonorientable Genus of the Generalized Unit and Unitary Cayley Graphs of a Commutative Ring

Let [Formula: see text] be a commutative ring and [Formula: see text] the multiplicative group of unit elements of [Formula: see text]. In 2012, Khashyarmanesh et al. defined the generalized unit and unitary Cayley graph, [Formula: see text], corresponding to a multiplicative subgroup [Formula: see text] of [Formula: see text] and a nonempty subset [Formula: see text] of [Formula: see text] with [Formula: see text], as the graph with vertex set [Formula: see text]and two distinct vertices [Formula: see text] and [Formula: see text] being adjacent if and only if there exists [Formula: see text] such that [Formula: see text]. In this paper, we characterize all Artinian rings [Formula: see text] for which [Formula: see text] is projective. This leads us to determine all Artinian rings whose unit graphs, unitary Cayley graphs and co-maximal graphs are projective. In addition, we prove that for an Artinian ring [Formula: see text] for which [Formula: see text] has finite nonorientable genus, [Formula: see text] must be a finite ring. Finally, it is proved that for a given positive integer [Formula: see text], the number of finite rings [Formula: see text] for which [Formula: see text] has nonorientable genus [Formula: see text] is finite.

Travelling Wave Antenna Based MIMO for 5GHz WLAN Band Application With Pattern Diversity

ABSTRACT A single-layer, four-element multiple-input-multiple-output (MIMO) antenna for 5 GHz (5150–5850 MHz) band WLAN application is proposed. Each unit element consists of three sections and this behaves as a travelling wave antenna, which enables frequency scanning feature. The combination of orthogonal feeds and placement of elements introduce dual-polarisation, and pattern diversity respectively. Thus, the proposed MIMO antenna offers a higher degree of freedom (pattern diversity, frequency scanning and dual polarisation), which makes it exceptional. The proposed MIMO antenna has a maximum impedance bandwidth of 17% (4.93–5.87 GHz) corresponding to port 4 and isolation of 17.5 dB, which is achieved without additional decoupling/isolation enhancement circuits. The envelope correlation coefficient of 0.25, capacity loss less than 0.4 bits/sec/Hz, and the mean effective gain (MEG) ratio of 0 dB in the desired frequency band quantifies the diversity performance for WLAN applications. The proposed MIMO has gain from 2 to 5.5 dB and occupies a compact volume of 1.3 λ × 1.3 λ × 0.02 λ mm3, which may be one of the most miniaturised electrical configurations.

Algebra of Borcherds products

Borcherds lift for an even lattice of signature ( p , q ) (p, q) is a lifting from weakly holomorphic modular forms of weight ( p − q ) / 2 (p-q)/2 for the Weil representation. We introduce a new product operation on the space of such modular forms and develop a basic theory. The product makes this space a finitely generated filtered associative algebra, without unit element and noncommutative in general. This is functorial with respect to embedding of lattices by the quasi-pullback. Moreover, the rational space of modular forms with rational principal part is closed under this product. In some examples with p = 2 p=2 , the multiplicative group of Borcherds products of integral weight forms a subring.

Compact Interlaced Dual Circularly Polarized Sequentially Rotated Dielectric-Resonator Antenna Array

In this study, a compact 2 × 2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications. The array is composed of a novel unit elements that are made of rectangular dielectric resonator (RDR) coupled to an eye slot for generating the orthogonal modes, and to acquire circular polarization (CP) radiation. For the purpose of miniaturization and achieving dual polarized resonance, the array is fed by two interlaced ports and each port excites two radiating elements. The first port feeds horizontal elements to obtain left hand circular polarization (LHCP). The second port feeds vertical elements to obtain right hand circular polarization (RHCP). A quarter-wave length transformer is employed to reduce the attenuation and consequently increase the array gain performance. The 35 × 35 mm2 () gains were 8.4 and 8.2 dBi for port 1 and port 2, respectively, with port isolations of −33.51 dB. The design achieves a voltage standing-wave ratio (VSWR) < −10 dB and an axial ratio (AR) ˂ − 3 dB bandwidth of 2.48% (5.766 to 5.911 GHz) for LHCP at port 1 and a VSWR < −10 dB and AR ˂ −3 dB bandwidth of 2.28% (5.788 to 5.922 GHz) for RHCP at port 2. The findings of the proposed design validate its use for ISM band applications.

РЕКОМЕНДАЦІЇ НАЧАЛЬНИКУ ПРИКОРДОННОГО ПІДРОЗДІЛУ ЩОДО ОРГАНІЗАЦІЇ ЙОГО ДІЙ В УМОВАХ ПРИПИНЕННЯ ЗБРОЙНОЇ ПРОВОКАЦІЇ НА ДЕРЖАВНОМУ КОРДОНІ

The relevance of the article is determined by the need to counter threats to border security in the conditions of armed aggression by the Russian Federation. In the conditions of various types of armed provocations by Russia on the state border, attempts to penetrate the Ukrainian territory by subversive and intelligence groups, border units, state border guard units, and border infrastructure also become the object of such provocations. Therefore, the task of developing recommendations to the head of the border unit regarding the organization of his actions in the conditions of the cessation of armed provocation on the state border is relevant and contains the practical significance of the topic chosen for study. On the basis of the analysis of scientific literature, normative legal acts, and the experience of performing official and combat tasks by border units, develop recommendations to the head of the border unit regarding the organization of his actions in the conditions of the cessation of armed provocation on the state border. Scientific analysis of the research problem; generalization and systematization of theoretical information and practical actions of border units regarding the cessation of armed provocations; comparison, classification, induction and deduction. It has been established that the content of the work of the head of the border unit in countering armed provocations will depend on: the nature of the enemyꞌs actions, the characteristics of the border unit, the availability of forces and means, and other factors. It includes: determining the measures that must be taken immediately to prepare the unit for action as soon as possible; assessment of the situation; decision-making; definition of tasks for the elements of the order of battle; organization of interaction, comprehensive support and management. Each item of the content of the work of the head of the border division is disclosed. Also, based on the experience of tactical role-playing games, a version of the combat order of the head of the border unit was proposed and its content was revealed. A feature of the developed recommendations to the head of the border unit regarding the organization of his actions in the conditions of stopping armed provocation at the state border is their practical focus. They are intended for the heads of the lowest levels of state border protection, who are direct executors of the tasks of the border department for the protection and protection of the state border. Based on the analysis of crisis situations on the state border, the purpose and objects of armed provocations, as well as the tactics of the enemyꞌs actions during their implementation, are summarized. The content of the work of the head of the border unit regarding the organization of his actions in the conditions of the cessation of armed provocation on the state border has been specified and revealed. A variant of the combat order of the head of the border unit is proposed. The prospects for further research in this direction can be seen in a more detailed study of the order of actions of the elements of the border unit's combat order when stopping armed provocation on the state border.

Justification of the working elements of a transport unit for the preparation of cereal flakes

The conducted research is aimed at improving the efficiency of a trailed transport unit for grain crushing. The purpose of these studies is the theoretical justification of parameters of conical working bodies of grain crushing (milling) to obtain grain flakes in the conditions of small farms using a mobile unit. The research methodology provided a theoretical justification of design and kinematic parameters of the crushing working body of the disk crusher (breaker) of the transport unit. The force analysis of interaction of discs with a particle was carried out, differential equations for determination of law of particle gravity centre movement between discs were solved, correlation of discs diameter and particle size was revealed, final thickness of a particle at operation of a trailed milling unit was determined.

Development of Beam Steerable Reflectarray With Liquid Crystal for Both E-Plane and H-Plane

In this paper, a reconfigurable reflectarray (RA) with two-finger element composed of electrically biased liquid crystal (LC) at millimeter wave band is proposed. An orthogonal bias network is proposed and developed, which can result in changes in the equivalent relative permittivity of the liquid crystal, and reflection phase along direction <inline-formula> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> and direction <inline-formula> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> can be realized, thus beam steering at both E-plane and H-plane can be achieved. The LC RA is composed of 10 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 10 elements of 2-finger unit, a standard horn antenna is obliquely placed as feed, and radiation pattern is calculated by array synthesis and full wave simulation. It is found that beam scan at both E-plane and H-plane can be achieved. Compared with former researches of LC RA, this work introduces a simple scheme to achieve beam scan for LC RA at both E-plane and H-plane.

交通通达度对生态系统健康的影响——以长江中游城市群为例

PDF HTML阅读 XML下载 导出引用 引用提醒 交通通达度对生态系统健康的影响——以长江中游城市群为例 DOI: 10.5846/stxb202101230245 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（42001187，42001231，41701629）；地表过程与资源生态国家重点实验室开放基金项目（2021-KF-03） Impact of traffic accessibility on ecosystem health: A case study of the middle reaches of the Yangtze River Urban Agglomerations Author: Affiliation: Fund Project: National Natural Science Foundation of China, No.42001187 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:完善的交通基础设施网络是形成高度同城化和高度一体化城市群的前提和基础，科学探测城市群地区交通通达度对生态系统健康状况的影响机理对城市群地区生态系统保护以及区域可持续发展具有重要实践意义和价值。基于多源数据分别测度了1995-2015年长江中游城市群交通通达度以及生态系统健康水平，并借助双变量空间自相关与空间回归模型从全局和局部的角度揭示了交通通达度对生态系统健康的影响机理。研究结果显示：（1）研究期间长江中游城市群生态系统健康状况总体呈现降低态势，山区生态系统健康水平显著高于平原地区；（2）双变量空间自相关分析结果显示交通通达度和生态系统健康水平之间存在显著的空间依赖性，二者之间主要的关系类型包括低交通通达度水平-低生态系统健康水平、高交通通达度水平-低生态系统健康水平和低交通通达度水平-高生态系统健康水平三种类型；（3）空间回归结果显示交通通达度的增加会导致生态系统健康状况的恶化，而且交通通达度对生态系统健康的影响具有显著的空间异质性。研究发现可以为长江中游城市群地区生态系统健康保护宏观调控政策制定以及差异化管控政策制定提供科学依据。 Abstract:The gradual improvement of traffic network in urban agglomeration plays an important role in the construction of national land development environment, construction of national land development structure, and optimization of functional space system. At the same time, it also causes serious disturbance to the structure and function of ecosystem and the health status of ecosystem, and seriously threatens the sustainable development of urban agglomeration. How to promote the high-quality development of urban agglomerations and alleviate the disturbance and damage of urban agglomerations to ecosystem health has become an urgent problem to be answered and solved in the current development process of urban agglomerations. To scientifically reveal the spatial relationship between traffic accessibility and ecosystem health in urban agglomerations, and to clarify the impact mechanism of traffic accessibility on ecosystem health is an effective way to solve this issue. Based on multi-source data, this study measured the traffic accessibility and ecosystem health level in the middle reaches of the Yangtze River Urban Agglomerations (MRYRUA) from 1995 to 2015, and estimated the influence mechanism of traffic accessibility on ecosystem health with bivariate spatial autocorrelation and an integrated spatial regression models from the global and local perspectives. The results showed that:(1) the overall ecosystem health in the MRYRUA exhibited a decreasing trend, and the ecosystem health level in the mountainous areas were significantly higher than those of the plain areas during the study period. (2) The bivariate spatial autocorrelation results showed that there was a significantly spatial dependence between traffic accessibility and ecosystem health. The spatial relationships between them mainly included low traffic accessibility-low ecosystem health level, high traffic accessibility-low ecosystem health level, and low traffic accessibility-high ecosystem health level. (3) The spatial regression results showed that traffic accessibility development would lead to the deterioration of ecosystem health. The impact of traffic accessibility on ecosystem health had significantly spatial heterogeneity. The results show that the ecosystem health is not only affected by the ecosystem elements of the local unit, but also by the health status of the surrounding units or distant units and other factors. Therefore, the trans-regional joint governance is particularly important in urban agglomeration. Secondly, the results show that the impact of traffic accessibility on ecosystem health has significant spatial heterogeneity, and local differentiated management and control measures for regional future traffic construction and ecosystem health protection are necessary for the sustainable development of urban agglomerations. The findings can provide a scientific basis for the formulation of macro-control policies for ecosystem health protection and differentiated control policies for urban agglomerations in the MRYRUA. 参考文献 相似文献 引证文献

Design of a High Linearity Sinusoidal Current Generator Using Shifting Current Mirror Architecture

To develop a simple current generator (CG) for bio-impedance (BioZ) and electrical impedance tomography (EIT) systems, this paper proposes using a shifting-current-mirror (S-CM) architecture to realize a high linearity sinusoidal CG. The proposed S-CM CG controls the amplitude of its output by selecting the unit elements using data weighted averaging (DWA) at every clock cycle, thus suppressing the mismatch. The proposed current generator has shown an improvement in the average signal-to-noise-and-distortion ratio (SNDR) of up to 4.78 dB with DWA for resolutions up to 14 bits and has high linearity for resolutions up to 14 bits, 12 bits, and 10 bits while having area savings of 5×, 10×, and 20×, respectively.

Максимальная группа изометрий лоренцевой группы Ли 𝐴+(1) × 𝐴+(1)

We consider a connected simply connected four-dimensional Lie group𝐺𝐼𝑉 , whose Lie algebra belongs to the IV Bianchi type. It is proved that there is only one way of defining a left-invariant Lorentzian metric on it, for which the full isometry group of the resulting homogeneous manifold is five-dimensional. In the coordinates associated with the matrix representation of the Lie group, the matrix of the metric tensor is found and formulas are written according to which the one-parameter group of isometries acts, which leaves the unit element of the Lie group fixed. Also, formulas are written out according to which the full group of isometries acts.

A Single-Layer Broadband Reflectarray in K-Band Using Cross-Loop Slotted Patch Elements

A broadband linearly polarized reflectarray antenna is designed by modifying a typically narrowband square patch unit element with cross-loop slot (CLS). Due to the introduction of the CLS, the unit patch element becomes multi-resonant and miniaturized. Besides, the outer length and width of the CLS are one-to-one related to the length of the patch. As a result, more than 480° phase range with quite good linearity is achieved. In addition, the phase ranges are almost parallel to each other from 22.5–26.5 GHz, which signifies its broadband property. Using such <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$36\times 36$ </tex-math></inline-formula> CLS patches in a square aperture of 180 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times180$ </tex-math></inline-formula> mm size, an offset-fed reflectarray is constructed for an off-broadside radiation pattern. A prototype has been fabricated to experimentally validate the numerical results obtained using CST full-wave simulations. The measurement results exhibit a broad 1-dB gain bandwidth of 17.6% (22.44–26.78 GHz) and a peak gain of 32.2 dBi with an aperture efficiency of 60.6%. Moreover, both the cross-pol and side-lobe levels (SLLs) remain more than 40 dB and 21 dB, respectively, below the peak co-pol level throughout the 1-dB gain bandwidth. The proposed reflectarray can be used as a CubeSat antenna for K-band inter-satellite links (ISL).

Conformal Quad-Port UWB MIMO Antenna for Body-Worn Applications

A conformal four-port multiple-input-multiple-output (MIMO) antenna operating at 2.4 GHz and ultrawideband (UWB) is presented for wearable applications. The unit element of the MIMO antenna is a simple rectangular monopole with an impedance bandwidth of 8.9 GHz (3.1–12 GHz). In the monopole radiator, stubs are introduced to achieve 2.4 GHz resonance. Also, a defect is introduced in the ground plane to reduce backside radiation. The efficiency of the proposed antenna is greater than 95%, and its peak gain is 3.1 dBi. The MIMO antenna has an isolation of &gt;20 dB, and the estimated specific absorption rate (SAR) values for 1 gm of tissue are below 1.6 W/Kg. The size of the four-port MIMO antenna is 1.38λ0 × 0.08λ0 × 0.014λ0.

РАЗРАБОТКА РЕТРАНСЛЯТОРА ДЛЯ УСТРОЙСТВА КОНТРОЛЯ ИЗМЕНЕНИЯ СОСТАВА ВОЗДУШНОЙ СРЕДЫ

This work is part of a project to create a device for monitoring changes in the composition of the air environment. The article describes the main elements of the repeater unit included in the measuring device. The results of modeling the developed band-pass filter, which is part of the waveguide path of the repeater, are presented. Experimental studies of the filter and circulator parameters are also carried out. The technical capabilities of the electronic part of the repeater unit, namely microwave amplifiers and a controlled phase shifter, are described.

Photoluminescence enhancement with all-dielectric coherent metasurfaces

Abstract Mie resonances have recently attracted much attention in research on dielectric metasurfaces, owning to their enriched multipole resonances, negligible optical loss, and efficient light emitter integration. Although there is a rapid advancement in this field, some fundamental developments are still required to provide a simpler and more versatile paradigm for photoluminescence (PL) control. In this work, we proposed that an all-dielectric coherent metasurface can engineer the PL response by tuning the array size. Such PL manipulation is attributed to the collective Mie resonances that mediate the inter-unit interactions between unit elements and alter the PL intensity. Metasurfaces with different chip sizes are utilized to explore the array size effect on the collective Mie resonances, field enhancement, and Q-factor in TiO2 metasurfaces. Incorporating the all-dielectric coherent metasurface with fluorescent photon emitters, we performed the dependence of PL enhancement on array size, which achieves an enhancement factor of ∼10 at the central area of a 90 × 90 μm2 TiO2 metasurface array. These findings provide an additional degree of freedom to engineer the near-field confinement and enhancement, allowing one to manipulate incoherent photon emission and tune light–matter interaction at the nanoscale.

A new software program for monitoring the energy distribution in a thermal waste treatment plant system

The paper presents a novel system for monitoring the operation of a thermal waste treatment plant. The computer program is based on measurements of pressure, temperature, and mass flow rate of the working medium. The boiler efficiency is calculated using an indirect method. Thermal online calculations of the boiler combustion chamber make it possible to determine the heat flow rate to the evaporator. Based on the energy balance of the boiler evaporator, the superheated steam mass flow rate is determined, taking into account the mass flow rates of water injected into steam attemperators. By comparing the calculated and measured value of steam mass flow rate, the calorific value of the fuel fed is determined. The developed system enables monitoring of energy flow rates in individual elements of the power unit, taking into account losses in the boiler and turbine condenser. The following parameters are determined online, the efficiency of the boiler and the entire incinerator, heat losses in the boiler and the turbine condenser, as well as the heat flow rate, supplied to the municipal district heating system. By monitoring the plant operation, it is possible to adjust online the optimum excess air ratio.

3D EM data‐driven artificial network‐based design optimization of circular reflectarray antenna with semi‐elliptic rings for X‐band applications

AbstractIn this work, the design and realization of a circular reflectarray antenna (CERA) with semi‐ elliptic rings are carried out for X‐band. In order to achieve a fast design optimization process, 3D EM simulated data‐driven multilayer perceptron neural network (MLP NN) model of the unit element is generated providing the unit reflection phase as a continuous function of the radii and gap of the ring for the width w = 0.5 mm on the FR4 with ∊r = 4.4, h = 1.5 mm. The proposed CERA consists of 148 unit cells taken symmetrical both in the Y and X‐axis. Thus, a meta‐heuristic optimization algorithm honey bee mating optimization (HBMO) is applied to 21 elements between 10 and 12 GHz to determine their optimal geometries for the required reflection angles according to the phasing scheme. The simulated and measured performances of the designed CERA have been found in good agreement and its performance is compared also with its counterpart designs in literature and resulted to exhibit superior performance.

Bandpass frequency selective surface with two sharp sidebands based on shunted quarter‐mode substrate integrated waveguide cavities

AbstractA new highly selective bandpass frequency selective surface (FSS) is proposed with sharp sidebands and low profile. The unit element is composed of two shunted quarter‐mode substrate integrated waveguide (QMSIW) cavities with different dimensions and L‐shaped slots etched on both sides of dielectric substrates. Two transmission zeros and three transmission poles are obtained by TM0.5,0.5,0 resonance of cavities, slot resonance, and the coupling between them, which yield a flat passband with steep roll‐off in both sidebands. As unit dimension is miniaturized using quarter‐mode resonance, the FSS presents good angular stability for dual polarization. Simulated results indicate that the passband with insertion loss less than 1 dB covers 8.86–9.57 GHz, while the transitional bandwidth at both sides of the passband is 27 and 25 MHz, respectively. A prototype was fabricated and measured, the experimental results of which verified the design.

On Laplacian spectrum of unitary Cayley graphs

Abstract Let R be a commutative ring with unity 1 ≠ 0 and let R× be the set of all unit elements of R. The unitary Cayley graph of R, denoted by GR = Cay(R, R×), is a simple graph whose vertex set is R and there is an edge between two distinct vertices x and y of R if and only if x − y ∈ R×. In this paper, we determine the Laplacian and signless Laplacian eigenvalues for the unitary Cayley graph of a commutative ring. Also, we compute the Laplacian and signless Laplacian energy of the graph GR and its line graph.

Tunable bandstop filter using graphene in terahertz frequency band

In this paper, a planar graphene-based bandstop filter is designed and simulated for the resonant frequency of 1THz. The transmission line model of the bandstop filter is considered, which consists of open-circuited shunt stubs that are interconnected through unit elements. The bandstop filter design is carried out from the normalized low pass Chebyshev prototype. By using frequency transformation, Richard’s transformation, and Kuroda’s identity, the desired bandstop filter can be designed from the low pass prototype. The graphene layer is introduced between the conductor layer and the dielectric for supporting the propagation of plasmonic waves. The simulation results show that the desired frequency response can be obtained for the designed graphene-based bandstop filter. By varying the chemical potential of the graphene layer, the resonant frequency of the bandstop filter can be tuned over the range of 0.1THz with the constant absolute bandwidth.