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Nematic liquid crystal/dimethylsulphoxide mixture based tuning condenser 向列液晶/二甲基亚砜混合物调谐电容器
Pub Date : 2020-06-04 DOI: 10.1088/2633-1357/ab8bc2
A. Parveen, Depanshu Varshney, J. Prakash
Here, we demonstrate experimentally the existence of temporally variable dielectric behavior of a nematic liquid crystal (NLC), the most widely used liquid crystal (LC) phase among all LCs materials, by mixing dimethylsulphoxide (DMSO) into former. The intermolecular interactions and nanosegregation of the molecular LC structures have influenced their self-assembly by mixing DMSO into it. We mainly examined the dielectric parameters such as dielectric permittivity, dielectric loss factor, and absorption/energy dissipation and observed that the NLC/DMSO mixture shows a nearly dielectric-conductor (D-C) transition as time passes. The presence of DMSO in this analysis was confirmed by Fourier transform infrared spectroscopy while time-dependent dielectric studies were carried out using dielectric spectroscopic techniques. The promising idea of showing D-C transition is truly proven that may open the possibilities for real-time variable and supercapacitors.
在这里,我们通过将二甲基亚砜(DMSO)混合到向列相液晶(NLC)中,实验证明了在所有液晶材料中最广泛使用的液晶(LC)相的介电行为存在时变。分子间相互作用和分子结构的纳米分离影响了DMSO的自组装。我们主要考察了介电常数、介电损耗因子和吸收/能量耗散等介电参数,并观察到随着时间的推移,NLC/DMSO混合物呈现出接近介电-导体(D-C)的转变。傅立叶变换红外光谱证实了DMSO的存在,同时使用介电光谱技术进行了随时间变化的介电研究。显示dc转换的有希望的想法被真正证明,这可能为实时可变电容器和超级电容器打开可能性。
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引用次数: 2
Predicting radiation treatment planning evaluation parameter using artificial intelligence and machine learning 利用人工智能和机器学习预测放射治疗计划评估参数
Pub Date : 2020-06-01 DOI: 10.1088/2633-1357/ab805d
Frederick F. C. Ng, R. Jiang, J. Chow
Purpose: This study suggested a new method predicting the dose-volume parameter for radiation treatment planning evaluation using machine learning, and to evaluate the performance of different learning algorithms in the parameter prediction. Methods: Dose distribution index (DDI) for fifty prostate volumetric modulated arc therapy plans were calculated, and compared to results predicted by machine learning using algorithms, namely, linear regression, tree regression, support vector machine (SVM) and Gaussian process regression (GPR). Root mean square error (RMSE), prediction speed and training time were determined to evaluate the performance of each algorithm. Results: From the results, it is found that the square exponential GPR algorithm had the smallest RMSE, relatively high prediction speed and short training time of 0.0038, 4,100 observation/s and 0.18 s, respectively. All linear regression, SVM and GPR algorithms performed well according to their RMSE in the range of 0.0038–0.0193. However, RMSE of the medium and coarse tree regression algorithms were found larger than 0.03, showing that they are not suitable for predicting DDI in this study. Conclusion: Machine learning can be used to predict dose-volume parameter such as DDI in radiation treatment planning QA. Selection of a suitable machine learning algorithm is important to determine the parameter effectively.
目的:本研究提出了一种利用机器学习预测放射治疗计划评估中剂量-体积参数的新方法,并评估不同学习算法在参数预测中的性能。方法:计算50种前列腺体积调制弧线治疗方案的剂量分布指数(DDI),并采用线性回归、树回归、支持向量机(SVM)和高斯过程回归(GPR)等算法与机器学习预测结果进行比较。通过确定均方根误差(RMSE)、预测速度和训练时间来评估每种算法的性能。结果:从结果来看,平方指数GPR算法的RMSE最小,预测速度较快,训练时间较短,分别为0.0038、4100观测/s和0.18 s。线性回归、SVM和GPR算法的RMSE均在0.0038 ~ 0.0193范围内,均表现良好。然而,发现中树和粗树回归算法的RMSE均大于0.03,表明它们不适合预测本研究中的DDI。结论:机器学习可用于预测放射治疗计划QA中的DDI等剂量-体积参数。选择合适的机器学习算法是有效确定参数的关键。
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引用次数: 16
Numerical simulation on the effect of sample geometry size on the metal flow behaviour during the forging process 锻造过程中试样几何尺寸对金属流动特性影响的数值模拟
Pub Date : 2020-05-29 DOI: 10.1088/2633-1357/ab828c
J. Obiko, F. Mwema
This paper reports on the effect of sample geometry size on the metal flow behaviour using DeformTM 3D finite element simulation software. The simulation process was done at forging temperature of 1100 °C and upper die speed of 50 mm/second. The friction coefficient between the die and the sample interface was taken to be constant during the simulation process. The results of the effective stress and strain distribution in the deformed sample were reported. The results show that the effective stress and strain distribution in the deformed sample was non-uniformly distributed. The maximum effective strain occurred at the centre of the deformed sample for all the samples tested. The maximum effective stress occurred at the die-sample contact surface. At the contact surfaces, the effective stress decreased with a decrease in the sample size. The effective stress at the centre of the deformed sample increased with a decrease in the sample geometry size.
本文使用DeformTM三维有限元模拟软件研究了样品几何形状对金属流动行为的影响。模拟过程是在1100°C的锻造温度和50mm/s的上模速度下进行的。在模拟过程中,模具和样品界面之间的摩擦系数取为常数。报道了变形试样的有效应力和应变分布结果。结果表明,变形试样的有效应力和应变分布不均匀。对于所有测试样品,最大有效应变发生在变形样品的中心。最大有效应力发生在模具样品接触表面。在接触表面,有效应力随着样品尺寸的减小而减小。变形样品中心的有效应力随着样品几何形状尺寸的减小而增加。
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引用次数: 3
Welcome to IOP SciNotes—a new open access journal for short research outputs across the physical and environmental sciences 欢迎来到IOP sciinotes,这是一份新的开放获取期刊,提供物理和环境科学领域的短期研究成果
Pub Date : 2020-05-29 DOI: 10.1088/2633-1357/ab9221
Lauren Carter
IOP SciNotes is a peer-reviewed, open access journal from IOP Publishing that enables researchers across the physical and environmental sciences to publish shorter research results (and other related outputs) which may not be suited to the traditional full-length journal article format. Adopting open science practices IOP SciNotes has been designed to provide authors with publication credit for individual stages or units of their research work, allowing anyone to validate, share and discover a wider range of scientific material associated with the research process.
IOP sciinotes是IOP Publishing出版的同行评议的开放获取期刊,它使物理和环境科学领域的研究人员能够发表可能不适合传统全文期刊文章格式的较短的研究结果(以及其他相关产出)。采用开放科学实践IOP sciinotes旨在为作者提供其研究工作的各个阶段或单位的出版信誉,允许任何人验证,分享和发现与研究过程相关的更广泛的科学材料。
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引用次数: 0
Molecular spectroscopy and adverse optical properties of N-(p-hexyloxy-benzylidene)–p-toluidine (HBT) liquid crystal molecule studied by DFT methodology DFT方法研究N-(对己基氧基-亚苄基)-对甲苯苯胺(HBT)液晶分子的分子光谱和不利光学性质
Pub Date : 2020-05-29 DOI: 10.1088/2633-1357/ab7f83
Narinder Kumar, Pawan Singh, K. Thapa, Devesh Kumar
In present work, we report the N-(p-hexyloxy-benzylidene)–p-toluidine (HBT) liquid crystal (LC) molecule having maximum absorbance due to the O–C stretching (carbon atom of benzene ring) during the intermolecular interaction. Under the expansion of an external electric field, the HBT LC having nematic to smectic phase stability with adverse (negative values) order parameter and birefringence. The refractive index expresses stability in the nematic, smectic, and isotropic phases. The director angle maintains stability for the nematic phase in the adverse order and smectic phase stable in positive order.
在本工作中,我们报道了N-(对己基氧基-亚苄基)-对甲苯苯胺(HBT)液晶(LC)分子在分子间相互作用过程中由于O–C拉伸(苯环的碳原子)而具有最大吸光度。在外部电场的扩展下,HBT LC具有向列相到近晶相的稳定性,具有不利(负值)的阶参数和双折射。折射率表示向列相、近晶相和各向同性相中的稳定性。指向矢角保持向列相在相反顺序的稳定性和近晶相在正顺序的稳定性。
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引用次数: 11
An Internet of Things app for monitor unit calculation in superficial and orthovoltage skin therapy 物联网应用程序,用于表面和正电压皮肤治疗中的监测单元计算
Pub Date : 2020-05-29 DOI: 10.1088/2633-1357/ab8be0
J. Pearse, J. Chow
Purpose: We developed an app for Internet of Things (IoT) device such as smartphone or tablet to calculate the monitor unit in superficial and orthovoltage skin therapy. The app can run both on the Windows and Android operation system. Methods: The IoT app was created based on the formula to calculate the monitor unit in skin therapy using kV photon beams. The calculation was based on databases of dose variables such as relative exposure factor and backscatter factor. The calculation also considered the stand-off and stand-in correction according to the inverse-square and inverse-cube law. Verification of the app was carried out by comparing the monitor unit results with those from hand calculations. Results: The frontend window of the app provided a user-friendly interface to the user for inputting prescription dose, beam and treatment setup variables. The user could save the calculation record electronically, generate a printout or send it to other radiation staff using the IoT. Verification of the app showing that deviation between the monitor units calculated by the app and by hand is insignificant. Conclusion: The verified IoT app can effectively calculate the monitor unit in superficial and orthovoltage skin therapy. The app takes advantages of all innate features of IoT such as real time communication, Internet access, data transfer and sharing.
目的:开发一款应用于智能手机或平板电脑等物联网设备的应用程序,用于计算浅表和正压皮肤治疗中的监护单位。这款应用可以在Windows和Android操作系统上运行。方法:根据千伏光子束皮肤治疗中监测单元的计算公式,创建物联网应用程序。计算基于相对暴露因子和后向散射因子等剂量变量数据库。计算中还考虑了根据平方反比和立方反比定律进行的隔离和隔离校正。通过将监测单元的结果与手工计算的结果进行比较,对应用程序进行了验证。结果:app前端窗口为用户输入处方剂量、剂量、治疗设置变量提供了友好的界面。用户可以通过电子方式保存计算记录,生成打印输出或使用物联网将其发送给其他辐射人员。应用程序的验证表明,应用程序计算的监视器单元与手动计算的监视器单元之间的偏差微不足道。结论:经验证的物联网应用程序可以有效地计算浅表和正压皮肤治疗中的监护单位。该应用程序充分利用了物联网的所有固有功能,如实时通信、互联网接入、数据传输和共享。
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引用次数: 9
Graphite fabric reinforced PAEK composites by novel impregnation-co-film technique 新型浸渍共膜技术在石墨织物增强PAEK复合材料中的应用
Pub Date : 2020-05-26 DOI: 10.1088/2633-1357/ab8d1a
U. Marathe, Meghashree Padhan, J. Bijwe
High performance polymers such as Poly(ether ether ketone) (PEEK), Poly(aryl ether ketone) (PAEK), Poly(ether ketone ketone) (PEKK), etc exhibit high melting points, 343 °C, 373 °C and 338 °C respectively and very high melt viscosity. They do not have appropriate solvents, which could open the ways to process their fabric reinforced composites; by impregnation technique followed by compression molding. Film stacking and powder sprinkling are the only possible techniques, which lead to weak crossover points due to non-wetting by the resin and finally resulting in inferior mechanical and interfacial properties and high amount of voids. In order to solve these problems, a novel technique called impregnation-co-film (ICF) is explored in this work. Polyetherimide (PEI) (10 wt% in dichloromethane solution) pre-impregnated graphite fabric prepregs were used before applying film technique followed by compression molding. The study compares properties such as density, void content, flexural strength, impact strength, Interlaminar shear strength (ILSS), thermal stability (in air) and interface by field emission scanning electron microscopy for the composite prepared with film stacking technique and that by impregnation-co-film stacking technique. It was confirmed that the new ICF technique proved to be significantly promising than the older technique almost in all aspects with 120% improvement in ILSS, 127% in flexural strength and 200% decrease in void content.
高性能聚合物如聚醚醚酮(PEEK)、聚芳醚酮(PAEK)、聚醚酮酮(PEKK)等具有高熔点,熔点分别为343℃、373℃和338℃,熔体粘度非常高。他们没有合适的溶剂,这可能为加工织物增强复合材料开辟道路;通过浸渍技术,然后是压缩成型。薄膜堆积和粉末喷洒是唯一可行的技术,由于树脂不润湿,导致交叉点弱,最终导致较差的机械性能和界面性能以及大量的空隙。为了解决这些问题,本文探索了一种新型的浸渍-共膜(ICF)技术。采用聚醚酰亚胺(PEI) (10 wt%在二氯甲烷溶液中)预浸渍石墨织物预浸料,然后应用薄膜技术进行压缩成型。通过场发射扫描电镜对膜层技术和浸渍-共膜层技术制备的复合材料的密度、孔隙含量、抗折强度、冲击强度、层间剪切强度(ILSS)、热稳定性(空气中)和界面等性能进行了比较。结果表明,新ICF技术几乎在所有方面都比旧技术有显著的发展前景,ILSS提高120%,抗弯强度提高127%,空隙率降低200%。
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引用次数: 2
S-band electron spin resonance spectroscopy using a short-circuited coplanar waveguide resonator 利用短路共面波导谐振器的s波段电子自旋共振光谱
Pub Date : 2020-04-17 DOI: 10.1088/2633-1357/abc870
Subhadip Roy, A. Nandi, P. Das, C. Mitra
In this work, we study the development of a coplanar waveguide (CPW) resonator and its use in an electron spin resonance (ESR) spectrometer. The CPW resonator is designed to operate in S-band (2-4 GHz), with a short circuit configuration leading to miniaturization. It is so constructed such that it has a characteristic impedance of 50 ohms. The resonator supports quasi-TEM mode of propagation owing to its uniplanar nature, demanding detailed electromagnetic simulation. The design parameters and the electromagnetic field distribution are obtained from the simulation. The resonator is fabricated using optical lithography with a rapid prototyping technique. The characteristic response of the resonator is measured by coupling it to a Vector Network Analyzer (VNA). The ESR absorption spectrum of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) is captured by using this resonator in reflection geometry. The microwave magnetic field distribution at the sample position is investigated. The ascertained value of Lande g-factor is consistent with that reported in the literature. Spin sensitivity of the order of 1015 spins/gauss is achieved upon using this resonator at room temperature. The quality factor of this resonator is found to be low and this makes it suitable for use in a Pulsed ESR spectrometer.
在这项工作中,我们研究了共面波导(CPW)谐振器的发展及其在电子自旋共振(ESR)光谱仪中的应用。CPW谐振器设计为在S波段(2-4 GHz)工作,短路配置可实现小型化。它的结构使得它具有50欧姆的特性阻抗。谐振器由于其单极性而支持准TEM传播模式,需要详细的电磁模拟。通过仿真得到了设计参数和电磁场分布。谐振器是使用光学光刻和快速原型技术制造的。谐振器的特性响应是通过将其耦合到矢量网络分析器(VNA)来测量的。利用该谐振腔在反射几何中捕获了自由基2,2-二苯基-1-苦基肼(DPPH)的ESR吸收光谱。研究了样品位置的微波磁场分布。Lande g因子的确定值与文献中报道的值一致。在室温下使用该谐振器可获得1015自旋/高斯量级的自旋灵敏度。发现这种谐振器的品质因数低,这使得它适合在脉冲ESR光谱仪中使用。
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引用次数: 1
MNIST-MIX: a multi-language handwritten digit recognition dataset mist - mix:多语言手写数字识别数据集
Pub Date : 2020-04-08 DOI: 10.1088/2633-1357/abad0e
Weiwei Jiang
In this note, we contribute a multi-language handwritten digit recognition dataset named MNIST-MIX, which is the largest dataset of the same type in terms of both languages and data samples. With the same data format with MNIST, MNIST-MIX can be seamlessly applied in existing studies for handwritten digit recognition. By introducing digits from 10 different languages, MNIST-MIX becomes a more challenging dataset and its imbalanced classification requires a better design of models. We also present the results of applying a LeNet model which is pre-trained on MNIST as the baseline.
在本说明中,我们提供了一个名为MNIST-MIX的多语言手写数字识别数据集,它是同类型语言和数据样本中最大的数据集。使用与MNIST相同的数据格式,MNIST-MIX可以无缝地应用于现有的手写数字识别研究中。通过引入来自10种不同语言的数字,MNIST-MIX成为一个更具挑战性的数据集,其不平衡分类需要更好的模型设计。我们还介绍了应用在MNIST上预训练的LeNet模型作为基线的结果。
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引用次数: 11
Multi-Class classification of vulnerabilities in smart contracts using AWD-LSTM, with pre-trained encoder inspired from natural language processing 使用AWD-LSTM对智能合约中的漏洞进行多类分类,预训练编码器的灵感来自自然语言处理
Pub Date : 2020-03-21 DOI: 10.1088/2633-1357/abcd29
Ajay K. Gogineni, S. Swayamjyoti, Devadatta Sahoo, K. Sahu, R. Kishore
Vulnerability detection and safety of smart contracts are of paramount importance because of their immutable nature. Symbolic tools like OYENTE and MAIAN are typically used for vulnerability prediction in smart contracts. As these tools are computationally expensive, they are typically used to detect vulnerabilities until some predefined invocation depth. These tools require more search time as the invocation depth increases. Since the use of smart contracts increases rapidly, their analysis becomes difficult using these traditional tools. Recently, a machine learning technique called Long Short Term Memory (LSTM) has been used to predict the vulnerability of a smart contract. In the present article, we present how to classify smart contracts into Suicidal, Prodigal, Greedy, or Normal categories using Average Stochastic Gradient Descent Weight-Dropped LSTM (AWD-LSTM), a variant of LSTM. We reduced the class imbalance by considering only distinct opcode combinations for normal contracts and achieved a weighted average F1 score of 90.0%. Such techniques can be utilized in real-time to analyze a large number of smart contracts and to improve their security.
智能合约的漏洞检测和安全至关重要,因为它们具有不可变的性质。OYENTE和MAIAN等符号工具通常用于智能合约中的漏洞预测。由于这些工具的计算成本很高,它们通常用于检测漏洞,直到达到某种预定义的调用深度。随着调用深度的增加,这些工具需要更多的搜索时间。由于智能合约的使用迅速增加,使用这些传统工具对其进行分析变得困难。最近,一种名为长短期内存(LSTM)的机器学习技术已被用于预测智能合约的漏洞。在本文中,我们介绍了如何使用LSTM的一种变体——平均随机梯度下降加权LSTM(AWD-LSTM)将智能合约分类为自杀、浪子、贪婪或正常类别。我们通过只考虑正常合同的不同操作码组合来减少类不平衡,并获得90.0%的加权平均F1分数。这些技术可以实时用于分析大量智能合同并提高其安全性。
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引用次数: 15
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