检索结果-南通市图书馆

Influence of thyroid volume reduction on absorbed dose in ^(131)I therapy studied by using Geant4 Monte Carlo simulation

引用

Chinese Physics C 2014年第5期38卷 62-68页

作者： Ziaur Rahman Sikander M Mirza waheed Arshed Nasir M Mirza waheed ahmed Health Physics Division Pakistan Institute of Nuclear Science and Technology Department of Physics and Applied Mathematics Pakistan Institute of Engineering and Applied Sciences

A simulation study has been performed to quantify the effect of volume reduction on the thyroid absorbed dose per decay and to investigate the variation of energy deposition per decay due to β- and γ-activity of 131I with volume/mass of thyroid, for water, ICRP- and ICRU-soft tissue taken as thyroid material. A Monte Carlo model of the thyroid, in the Geant4 radiation transport simulation toolkit was constructed to compute the β- and γ-absorbed dose in the simulated thyroid phantom for various values of its volume. The effect of the size and shape of the thyroid on energy deposition per decay has also been studied by using spherical, ellipsoidal and cylindrical models for the thyroid and varying its volume in 1-25 cm3 range. The relative differences of Geant4 results for different models with each other and MCNP results lie well below 1.870%. The maximum relative difference among the Geant4 estimated results for water with ICRP and ICRU soft tissues is not more than 0.225%. S-values for ellipsoidal, spherical and cylindrical thyroid models were estimated and the relative difference with published results lies within 3.095%. The absorbed fraction values for beta particles show a good agreement with published values within 2.105% deviation. The Geant4 based simulation results of absorbed fractions for gammas again show a good agreement with the corresponding MCNP and EGS4 results （±6.667%） but have 29.032% higher values than that of MIRD calculated values. Consistent with previous studies, the reduction of the thyroid volume is found to have a substantial effect on the absorbed dose. Geant4 simulations confirm dose dependence on the volume/mass of thyroid in agreement with MCNP and EGS4 computed values but are substantially different from MIRD8 data. Therefore, inclusion of size/mass dependence is indicated for 131I radiotherapy of the thyroid.

关键词： mean absorbed dose rate Geant4 Monte Carlo simulation and 131I therapy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Progressive Approach to Generic Object Detection: A Two-Stage Framework for Image Recognition

引用

Computers, Materials & Continua 2023年第6期75卷 6351-6373页

作者： Muhammad Aamir Ziaur Rahman waheed ahmed Abro Uzair Aslam Bhatti Zaheer ahmed Dayo Muhammad Ishfaq College of Computer Science Huanggang Normal UniversityHuanggangHubei438000China FAST School of Computing National University of Computer&Emerging Science(NUCES)Karachi CampusKarachi75030Pakistan School of Information and Communication Engineering Hainan UniversityHaikou68000China

Object detection in images has been identified as a critical area of research in computer vision image *** has developed several novel methods for determining an object’s location and category from an ***,there is still room for improvement in terms of detection *** study aims to develop a technique for detecting objects in *** enhance overall detection performance,we considered object detection a two-fold problem,including localization and *** proposed method generates class-independent,high-quality,and precise proposals using an agglomerative clustering *** then combine these proposals with the relevant input image to train our network on convolutional ***,a network refinement module decreases the quantity of generated proposals to produce fewer high-quality candidate ***,revised candidate proposals are sent into the network’s detection process to determine the object *** algorithm’s performance is evaluated using publicly available the PASCAL Visual Object Classes Challenge 2007(VOC2007),VOC2012,and Microsoft Common Objects in Context(MS-COCO)*** only 100 proposals per image at intersection over union((IoU)=0.5 and 0.7),the proposed method attains Detection Recall(DR)rates of(93.17%and 79.35%)and(69.4%and 58.35%),and Mean Average Best Overlap(MABO)values of(79.25%and 62.65%),for the VOC2007 and MS-COCO datasets,***,it achieves a Mean Average Precision(mAP)of(84.7%and 81.5%)on both VOC *** experiment findings reveal that our method exceeds previous approaches in terms of overall detection performance,proving its effectiveness.

关键词： Deep neural network deep learning features agglomerative clustering localizations refinement region of interest(ROI) object detection

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A Dual-Tree Complex Wavelet Transform-Based Model for Low-Illumination Image Enhancement

引用

Wuhan University Journal of Natural Sciences 2021年第5期26卷 405-414页

作者： GUAN Yurong Muhammad Aamir Ziaur Rahman Zaheer ahmed Dayo waheed ahmed Abro Muhammad Ishfaq HU Zhihua Department of Computer Science Huanggang Normal UniversityHuanggang 438000HubeiChina

Image enhancement is a monumental task in the field of computer vision and image *** methods are insufficient for preserving naturalness and minimizing noise in *** article discusses a technique that is based on wavelets for optimizing images taken in ***,the V channel is created by mapping an image’s RGB channel to the HSV color ***,the acquired V channel is decomposed using the dual-tree complex wavelet transform(DT-CWT)in order to recover the concentrated information within its high and low-frequency ***,an adaptive illumination boost technique is used to enhance the visibility of a low-frequency ***,anisotropic diffusion is used to mitigate the high-frequency component’s noise *** improve the results,the image is reconstructed using an inverse DT-CWT and then converted to RGB space using the newly calculated ***,images are white-balanced to remove color *** demonstrate that the proposed approach significantly improves outcomes and outperforms previously reported methods in general.

关键词： image enhancement dual-tree complex wavelet transform(DT-CWT) anisotropic diffusion low-light images

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nanosecond pulse and dual-wavelength Q-switched 1.5 μm fiber laser using MAX phase Cr2TiAlC2 saturable absorber

引用

Optoelectronics Letters 2025年第1期21卷 7-12页

作者： ahmed Shakir AL-HITI Hiba HASSAN Department of Electrical Engineering Faculty of Engineering University of Anbar Department of Laser and Optoelectronics Engineering University of Technology-Iraq

We demonstrated a new type of MAX phase material, chromium titanium aluminum carbide（Cr2TiAlC2） polymer film, to generate a passively Q-switched erbium-doped fiber laser（EDFL）. The film thickness was measured to be around 45 μm, which was fabricated using the embedding method with polyvinyl alcohol（PVA） polymer as hoster. The saturable absorber（SA） film demonstrates a dual-wavelength passively Q-switched EDFL which operates at 1 531 nm and 1 560.19 nm, respectively. The Q-switching pulse duration could be varied from 2.46 μs to 770 ns, while the repetition rate varied from 92.76 kHz to 106.6 kHz with an increasing input pumping range from 154 mW to 300 mW. The maximum output power and pulse energy of 15.05 mW and 141.18 nJ were obtained at the maximum input power of 300 mW, respectively.

关键词： Saturable absorbers

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Vascular endothelial growth factor:a double-edged sword in the development of white matter lesions

引用

Neural Regeneration Research 2025年第1期20卷 191-192页

作者： Narek Manukjan Daniel Fulton Zubair ahmed WMatthijs Blankesteijn Sébastien Foulquier Department of Pharmacology and Toxicology Maastricht UniversityMaastrichtThe Netherlands CARIM-School for Cardiovascular Diseases Maastricht UniversityMaastrichtThe Netherlands Neuroscience and Ophthalmology Institute of Inflammation and AgeingUniversity of BirminghamEdgbastonBirminghamUK Centre for Trauma Sciences Research University of BirminghamEdgbastonBirminghamUK MHeNs-School for Mental Health and Neuroscience Maastricht UniversityMaastrichtThe Netherlands Department of Neurology Maastricht University Medical CenterMaastrichtThe Netherlands

As the population ages,the burden of age-related diseases becomes ***,over 55 million people suffer from dementia worldwide,with Alzheimer’s disease being the most common ***,it is becoming clearer that underlying vascular pathology such as cerebral small vessel disease(cSVD)may be a more detrimental cause for dementia(Cuadrado-Godia et al.,2018).It is estimated that 10%-30%of the elderly population and 35%-90%of all dementia patients exhibit signs of *** term cSVD refers to pathology affecting the small vessels of the brain,which can lead to lacunar cerebral infarcts,enlarged perivascular spaces,and cortical hemorrhages(Cuadrado-Godia et al.,2018).CSVD is often associated with cognitive decline,gait problems,and dementia(Cuadrado-Godia et al.,2018).

关键词： pathology becoming white

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A survey on trust based detection and isolation of malicious nodes in ad-hoc and sensor networks

引用

Frontiers of Computer Science 2015年第2期9卷 280-296页

作者： Adnan ahmed Kamalrulnizam ABU BAKAR Muhammad Ibrahim CHANNA Khalid HASEEB Abdul waheed KHAN Faculty of Computing Universiti Teknologi Malaysia Johor Bahru 81310 Malaysia Department of Information Technology Quaid-e-Awam University of Engineering Science and Technology Nawabshah 67450 Pakistan

Mobile ad-hoc networks （MANETs） and wireless sensor networks （WSNs） have gained remarkable apprecia- tion and technological development over the last few years. Despite ease of deployment, tremendous applications and significant advantages, security has always been a challeng- ing issue due to the nature of environments in which nodes operate. Nodes＇ physical capture, malicious or selfish behav- ior cannot be detected by traditional security schemes. Trust and reputation based approaches have gained global recog- nition in providing additional means of security for decision making in sensor and ad-hoc networks. This paper provides an extensive literature review of trust and reputation based models both in sensor and ad-hoc networks. Based on the mechanism of trust establishment, we categorize the state- of-the-art into two groups namely node-centric trust mod- els and system-centric trust models. Based on trust evidence, initialization, computation, propagation and weight assign- ments, we evaluate the efficacy of the existing schemes. Fi- nally, we conclude our discussion with identification of some unresolved issues in pursuit of trust and reputation manage- ment.

关键词： trust reputation wireless sensor network mo-bile ad-hoc networks routing node misbehavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Resource Allocation and Optimization in Device-to-Device Communication 5G Networks

引用

Computers, Materials & Continua 2021年第10期69卷 1201-1214页

作者： Fahad ahmed Al-Zahrani Imran Khan Mahdi Zareei Asim Zeb Abdul waheed Computer Engineering Department Umm Al-Qura UniversityMecca24381Saudi Arabia Department of Electrical Engineering University of Engineering and Technology PeshawarP.O.B.814Pakistan Tecnologico de Monterrey School of Engineering and SciencesZapopan45201Mexico Department of Computer Science Abbottabad University of Science and TechnologyHavelian22500Pakistan Department of Information Technology Hazara University MansehraMansehra21120Pakistan School of Electrical and Computer Engineering Seoul National UniversitySeoul08826Korea

The next-generation wireless networks are expected to provide higher capacity,system throughput with improved energy *** of the key technologies,to meet the demand for high-rate transmission,is deviceto-device(D2D)communication which allows users who are close to communicating directly instead of transiting through base stations,and D2D communication users to share the cellular user chain under the control of the cellular *** a new generation of cellular network technology,D2D communication technology has the advantages of improving spectrum resource utilization and improving system throughput and has become one of the key technologies that have been widely concerned in the ***,due to the sharing of cellular network resources,D2D communication causes severe interference to existing cellular *** of the most important factors in D2D communication is the spectrum resources utilization and energy consumption which needs considerable attention from research *** address these issues,this paper proposes an efficient algorithm based on the idea of particle swarm *** main idea is to maximize the energy efficiency based on the overall link optimization of D2D user pairs by generating an allocation matrix of spectrum and *** D2D users are enabled to reuse multiple cellular user’s resources by enhancing their total energy efficiency based on the quality of service constraints and the modification of location and speed in particle *** constraint also provides feasibility to solve the original fractional programming *** results indicate that the proposed scheme effectively improved the energy efficiency and spectrum utilization as compared with other competing alternatives.

关键词： 5G networks D2D communication resource allocation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Clinical outcomes of moderate to severe COVID-19 patients receiving invasive vs. non-invasive ventilation

引用

Asian Pacific Journal of Tropical Medicine 2021年第4期14卷 176-182页

作者： Zubia Jamil Samreen Khalid Shahid Mumtaz Abbasi Yasir waheed Jamal ahmed Department of Medicine Foundation University Medical CollegeFoundation UniversityDHA Phase 1 Islamabad 44000Pakistan Fauji Foundation Hospital Rawalpindi 46000Pakistan Department of Multidisciplinary Lab Foundation University Medical CollegeFoundation UniversityDHA Phase 1 Islamabad 44000Pakistan Department of Pulmonology Fauji Foundation HospitalRawalpindi 46000Pakistan

Objective:To evaluate the in-hospital outcome of moderate to severe COVID-19 patients admitted in High Dependency Unit(HDU)in relation to invasive ***-invasive mode of ***:In this study,the patients required either non-invasive[oxygen≤10 L/min or>10 L/min through mask or nasal prongs,rebreather masks and bilevel positive airway pressure(BiPAP)]or invasive *** analysis of 30-day in hospital mortality in relation to use of different modes of oxygen,Kaplan Meier and log rank analyses were *** the end,independent predictors of survival were determined by Cox regression ***:Invasive ventilation was required by 15.1%patients while 84.9%patients needed non-invasive *** with evidence of thromboembolism,high inflammatory markers and hypoxemia mainly required invasive *** 30-day in hospital mortality was 72.7%for the invasive group and 12.9%for the non-invasive group(1.8%oxygen10 L/min,3.6%rebreather mask and 4.5%BiPAP).The median time from hospital admission to outcome was 7 days for the invasive group and 18 days for the non-invasive group(P<0.05).Age,presence of co-morbidities,number of days requiring oxygen,rebreather,BiPAP and invasive ventilation were independent predictors of ***:Invasive mechanical ventilation is associated with adverse outcomes possibly due to ventilator associated lung ***,protective non-invasive ventilation remains the necessary and safe treatment for severely hypoxic COVID-19 patients.

关键词： COVID-19 SARS-CoV-2 Non-invasive ventilation Respiratory insufficiency Hypoxia Mechanical ventilation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Machine Learning-based Stable P2P IPTV Overlay

引用

Computers, Materials & Continua 2022年第6期71卷 5381-5397页

作者： Muhammad Javid Iqbal Ihsan Ullah Muhammad Ali Atiq ahmed waheed Noor Abdul Basit Directorate of Information Technology Sardar Bahadur Khan Women’s UniversityQuettaPakistan Department of Computer Science and Information Technology University of BalochistanQuettaPakistan

Live video streaming is one of the newly emerged services over the Internet that has attracted immense interest of the service *** Internet was not designed for such services during its inception,such a service poses some serious challenges including cost and ***-to-Peer(P2P)Internet Protocol Television(IPTV)is an application-level distributed paradigm to offer live video *** terms of ease of deployment,it has emerged as a serious alternative to client server,Content Delivery Network(CDN)and IP multicast ***,P2P approach has struggled to provide the desired streaming quality due to a number of *** of peers in a network is one of themajor issues among *** of the existing approaches address this issue through older-stable *** paper first extensively investigates the older-stable principle to observe its validity in different *** is observed that the older-stable principle does not hold in several of ***,it utilizes machine learning approach to predict the stability of *** work evaluates the accuracy of severalmachine learning algorithms over the prediction of stability,where the Gradient Boosting Regressor(GBR)out-performs other ***,this work presents a proof-of-concept simulation to compare the effectiveness of older-stable rule and machine learning-based predictions for the stabilization of the *** results indicate that machine learning-based stability estimation significantly improves the system.

关键词： P2P IPTV live video streaming user behavior overlay networks stable peers machine learning

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

N-methyl-2-pyrrolidonium-based Br?nsted-Lewis acidic ionic liquids as catalysts for the hydrolysis of cellulose

引用

Science China Chemistry 2016年第5期59卷 564-570页

作者： Zheng Zhao Na Li Abdul waheed Bhutto ahmed A. Abdeltawab Salem S. Al-Deyab Guangqing Liu Xiaochun Chen Guangren Yu Beijing Key Laboratory of Membrane Science and Technology College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029China Department of Chemical Engineering Mehran University of Engineering and TechnologyJamshoro 76062Pakistan Petrochemicals Research Chair College of ScienceKing Saud UniversityRiyadh 11451Saudi Arabia

We experimentally studied the catalytic performances of a series of Brrnsted-Lewis acidic N-methyl-2-pyrrolidonium metal chlorides （[Hnmp]Cl/MClx, where M=Fe, Zn, A1, or Cu） for the hydrolysis of microcrystalline cellulose （MCC） and cotton to produce reducing sugar. A variety of factors, such as temperature, time, ionic liquid （IL） species, IL dosage, and the concentra- tion of the metal chloride were investigated. [Hnmp]Cl/FeCl3 presented the best hydrolysis performance, affording a 98.8% yield of total reducing sugar from MCC （1 h, 100 ℃, 0.1 g MCC, 0.2 g acidic IL, 2.0 g [Bmim]Cl as solvent）, which is better than or comparable to results previously obtained with other -SO3H functionalized acidic ILs. The hydrolysis performances of [Hnmp]Cl/MClx were rationalized using density functional theory calculations, which indicated that interactions between the metal chlorides and the cellulose, including charge-transfer interactions are important in the hydrolysis of cellulose and degra- dation of glucose. This work shows that Bronsted-Lewis acidic ILs are potential catalysts for the hydrolysis of cellulose to produce sugar.

关键词： cellulose hydrolysis ionic liquid density functional theory

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：