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A COMPARATIVE STUDY OF THE INVENTORY SYSTEM WITH SERVICE FACILITY AND POSTPONED DEMANDS

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Journal of Systems Science and Systems Engineering 2014年第2期23卷 176-195页

作者： J.Sebastian Arockia Jenifer b.sivakumar School of Mathematics Madurai Kamaraj University

In this article, we present a continuous review （s,S） inventory system with a service facility consisting of finite buffer （capacity N ） and a single server. The customers arrive according to a Poisson process. The individual customer＇s unit demand is satisfied after a random time of service, which is assumed to be exponential. When the inventory level drops to s＇an order for Q（= S-s） items is placed. The lead time of reorder is assumed to be exponential distribution. An arriving customer, who finds the buffer is full, enters into the pool of infinite size or leaves the system according to a bernolli trial. At the time of service completion, if the buffer size drops to a preassigned level L （1 〈 L 〈 N） or below and the inventory level is above s, we select the customers from the pool according to two different policy ： in first policy, with probability p （0 〈 p 〈 1） we select the customer from the head of the pool and we place the customer at the end of the buffer; in the second policy, with p （0 〈 p 〈 1） the customer from the pool is transferred to the buffer for immediate service and after completion of his service we provide service to the customer who is in the buffer with probability one. If at a service completion epoch the buffer turns out to be empty, there is at least one customer in the pool and the inventory level is positive, then the one ahead of all waiting in the pool gets transferred to the buffer, and his service starts immediately. The joint probability distribution of the number of customers in the pool, number of customers in the buffer and the inventory level is obtained in the steady-state case. Various stationary system performance measures are computed and total expected cost rate is calculated. A comparative result of two models is illustrate numerically.

关键词： Continuous review inventory system postponed demands service facility finite waiting hall pool with infinite size

Intelligent biomedical Electrocardiogram Signal Processing for Cardiovascular Disease Diagnosis

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Computers, Materials & Continua 2022年第4期71卷 255-268页

作者： R.Krishnaswamy b.sivakumar b.Viswanathan Fahd N.Al-Wesabi Marwa Obayya Anwer Mustafa Hilal Department of Electronics and Communication Engineering University College of Engineering AriyalurAriyalur621704India School of Computing SRM Institute of Science and TechnologyChennai603203India Department of Electronics and Communication Engineering K.Ramakrishnan College of EngineeringTiruchirappalli621112India Department of Computer Science Factually of Science&Art at MahayilKing Khalid UniversitySaudi Arabia Faculty of Computer and IT Sana’a UniversityYemen Department of biomedical Engineering College of EngineeringPrincess Nourah Bint Abdulrahman UniversitySaudi Arabia Department of Computer and Self Development Preparatory Year DeanshipPrince Sattam Bin Abdulaziz UniversityAlkharjSaudi Arabia

Automatic biomedical signal recognition is an important processfor several disease diagnoses. Particularly, Electrocardiogram (ECG) is commonly used to identify cardiovascular diseases. The professionals can determine the existence of cardiovascular diseases using the morphological patternsof the ECG signals. In order to raise the diagnostic accuracy and reduce thediagnostic time, automated computer aided diagnosis model is necessary. Withthe advancements of artificial intelligence (AI) techniques, large quantity ofbiomedical datasets can be easily examined for decision making. In this aspect,this paper presents an intelligent biomedical ECG signal processing (IbECGSP) technique for CVD diagnosis. The proposed IbECG-SP technique examines the ECG signals for decision making. In addition, gated recurrent unit(GRU) model is used for the feature extraction of the ECG signals. Moreover,earthworm optimization (EWO) algorithm is utilized to optimally tune thehyperparameters of the GRU model. Lastly, softmax classifier is employedto allot appropriate class labels to the applied ECG signals. For examiningthe enhanced outcomes of the proposed IbECG-SP technique, an extensivesimulation analysis take place on the PTb-XL database. The experimentalresults portrayed the supremacy of the IbECG-SP technique over the recentstate of art techniques.

关键词： biomedical signals ecg disease diagnosis artificial intelligence parameter tuning gru model

A PERISHAbLE INVENTORY SYSTEM WITH SERVICE FACILITIES, MAP ARRIVALS AND PH- SERVICE TIMES

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Journal of Systems Science and Systems Engineering 2007年第1期16卷 62-73页

作者： Paul MANUEL b. sivakumar G. ARIVARIGNAN Department of Information Science Kuwait University Kuwait. Department of Applied Mathematics and Statistics School of Mathematics Madurai Kamaraj University Madurai Tamilnadu India

We consider a continuous review perishable （s,S） inventory system with a service facility consisting of a waiting hall of finite capacity and a single server. We assume two types of customers, ordinary and negative, arrive according to a Markovian Arrival Process （MAP）. An ordinary customer joins the queue and a negative customer instead of joining the queue removes one ordinary customer from the queue. The removal rule adopted in this paper is RCE （removal of a customer from the end）. The individual customer＇s unit demand is satisfied after a random time of service which is assumed to have a phase-type distribution. The life time of each item and the lead time of the reorders have been assumed to be independent exponential distributions. The joint probability distribution of the number of customers in the system and the inventory level is obtained for the steady state case. Various stationary system performance measures are computed and the total expected cost rate is calculated. The results are illustrated numerically.

关键词： Stochastic inventory Markovian demands service facility positive lead time negative customers

Stabilizing Energy Consumption in Unequal Clusters of Wireless Sensor Networks

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Computers, Materials & Continua 2020年第7期64卷 81-96页

作者： Nithya Rekha sivakumar Department of Computer Sciences College of Computer and Information SciencesPrincess Nourah Bint Abdulrahman UniversityRiyadh11671Saudi Arabia

In the past few decades,Energy Efficiency(EE)has been a significant challenge in Wireless Sensor Networks(WSNs).WSN requires reduced transmission delay and higher throughput with high quality services,it further pays much attention in increased energy consumption to improve the network *** collect and transmit data Clustering based routing algorithm is considered as an effective *** Head(CH)acts as an essential role in network connectivity and perform data transmission and data aggregation,where the energy consumption is superior to non-CH *** clustering approaches attempts to cluster nodes of same ***,owing to randomly distributed node distribution,a cluster with equal nodes is not an obvious possibility to reduce the energy *** resolve this issue,this paper provides a novel,balanced-Imbalanced Cluster Algorithm(b-IbCA)with a Stabilized boltzmann Approach(SbA)that attempts to balance the energy dissipation across uneven clusters in WSNs.b-IbCA utilizes stabilizing logic to maintain the consistency of energy consumption among sensor nodes’.So as to handle the changing topological characteristics of sensor nodes,this stability based boltzmann estimation algorithm allocates proper radius amongst the sensor *** simulation shows that the proposed b-IbCA outperforms effectually over other approaches in terms of energy efficiency,lifetime,network stability,average residual energy and so on.

关键词： WSN stability cluster head node balancing average residual energy

An enhanced cosine-based visual technique for the robust tweets data clustering

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International Journal of Intelligent Computing and Cybernetics 2021年第2期14卷 170-184页

作者： Narasimhulu K. Meena Abarna K.T. sivakumar b. Annamalai University ChidambaramIndiaand Rajeev Gandhi Memorial College of Engineering and Technology NandyalIndia

Purpose-The purpose of the paper is to study multiple viewpoints which are required to access the more informative similarity features among the tweets documents,which is useful for achieving the robust tweets data clustering ***/methodology/approach-Let“N”be the number of tweets documents for the topics *** texts,punctuations and other symbols are removed,tokenization and stemming operations are performed in the initial tweets pre-processing ***-of-features are determined for the tweets;later tweets are modelled with the obtained bag-of-features during the process of topics *** of topics features are extracted for every tweet *** set of topics features of N documents are treated as *** key idea of the proposed work is to use multi-viewpoints in the similarity features *** following figure illustrates multi-viewpoints based cosine similarity computation of the five tweets documents(here N 55)and corresponding documents are defined in projected space with five viewpoints,say,v_(1),v_(2),v_(3),v4,and *** example,similarity features between two documents(viewpoints v_(1),and v_(2))are computed concerning the other three multi-viewpoints(v_(3),v4,and v5),unlike a single viewpoint in traditional cosine ***-Healthcare problems with tweets *** models play a crucial role in the classification of health-related tweets with finding topics(or health clusters)instead of finding term frequency and inverse document frequency(TF-IDF)for unlabelled ***/value-Topic models play a crucial role in the classification of health-related tweets with finding topics(or health clusters)instead of finding TF-IDF for unlabelled tweets.

关键词： Tweets data clustering Topic models TF-IDF Similarity features Visual technique VAT cVAT MVCS-VAT

SIMAP500: A novel risk score to identify recipients at higher risk of hepatocellular carcinoma recurrence following liver transplantation

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World Journal of Transplantation 2024年第3期14卷 132-143页

作者： Amr Alnagar Nekisa Zakeri Konstantinos Koilias Rosemary E Faulkes Rachel brown Owen Cain M Thamara P R Perera Keith J Roberts Rebeca Sanabria-Mateos David C bartlett Yuk Ting Ma Shivan sivakumar Shishir Shetty Tahir Shah bobby V M Dasari Department of HbP and Liver Transplantation Surgery Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Centre for Liver Research Institute of Biomedical ResearchBirmingham B152TTUnited Kingdom Department of Hepatology Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Department of Pathology University Hospitals Birmingham NHS Foundation TrustBirmingham B152GWUnited Kingdom Department of Oncology Queen Elizabeth HospitalUniversity Hospitals of BirminghamBirmingham B152GWUnited Kingdom

bACKGROUND Recurrence of hepatocellular carcinoma(HCC)following liver transplantation(LT)has a devastating influence on recipients’survival;however,the risk of recur-rence is not routinely *** stratification is vital with a long LT waiting time,as that could influence the recurrence despite strict listing *** This study aims to identify predictors of recurrence and develop a novel risk pre-diction score to forecast HCC recurrence following *** A retrospective review of LT for HCC recipients at University Hospitals bir-mingham between July 2011 and February *** and multivariate analyses were performed to identify recurrence predictors,based on which the novel SIMAP500(satellite nodules,increase in size,microvascular invasion,AFP>500,poor differentiation)risk score was *** 234 LTs for HCC were performed with a median follow-up of 5.3 *** developed in 25 patients(10.7%).On univariate analyses,RETREAT score>3,α-fetoprotein(AFP)at listing 100-500 and>500,bridging,increased tumour size between imaging at the listing time and explant histology,increase in the size of viable tumour between listing and explant,presence of satellite nodules,micro-and macrovascular invasion on explant and poor differentiation of tumours were significantly associated with recurrence,based on which,the SIMAP500 risk score is *** SIMAP500 demonstrated an excellent predictive ability(c-index=0.803)and outper-formed the RETREAT score(c-index=0.73).SIMAP500 is indicative of the time to disease *** SIMAP500 risk score identifies the LT recipients at risk of HCC *** stratification allows patient-centric post-transplant surveillance *** validation of the score is recommended.

关键词： Liver transplantation Hepatocellular carcinoma Recurrence Survival

Postharvest responses of hydroponically grown lettuce varieties to nitrogen application rate

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Journal of Integrative Agriculture 2019年第10期18卷 2272-2283页

作者： bevly M.Mampholo Martin Maboko Puffy Soundy Dharini sivakumar Phytochemical Food Network Research Group Department of Crop SciencesTshwane University of TechnologyPretoria 0001South Africa Agricultural Research Council–Roodeplaat Vegetable and Ornamental PlantPrivate Bag X293Pretoria 0001South Africa

Limited information is available on the influence of preharvest N application rates on postharvest quality of different lettuce genotypes. Two green leafy lettuce (Multigreen 1 and Multigreen 3) and red leafy lettuce (Multired 4) were grown in gravel film technique and fertigated with five different N application rates: 60, 90, 120, 150 and 180 mg L^-1. The 120 mg L^-1 N application is commercially recommended for lettuce. After harvest, lettuce samples were packed in a bioriented poly propylene packaging (5% O2 and 5% CO2) and held at 5°C and 85% RH for 3, 6, 9 and 12 days. The genotypes, preharvest N application rates and storage time affected the leaf colour coordinates, phenolic acids (dicaffeoyltataric acid, caffeoyl tartaric acid, 3-caffeoylquinic acid and 3,4-dihydroxycinnamic acid) and browning enzyme activities (phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD)). Lower rates of N application at preharvest stage showed higher weight loss with the storage time increasing in Multigreen 3. In Multigreen 1, colour coordinate b* value decreased remarkably with N application rates from 60 to 120 mg L^–1 due to the onset of browning during storage. While in Multigreen 3 and N application higher than 60 mg L^–1 influenced the decrease in b* value. browning occurred due to the increased activity of PAL enzyme and the availability of the substrates caftaric, chlorogenic, caffeic acids, PPO activity and production of browning pigments due to the activity of POD. Higher, N application rates (>120 mg L^–1) influenced the browning mechanism and showed brownish red leaves in Multired 4 during storage. Higher ascorbic acid concentration played a role in reducing the onset of browning in the fresh cuts leaves of Mulitired 4 and Multigreen 3 fertilized with lower preharvest lower N application rates (bic acid content and the phenolic acid components and extended the

关键词： Lactuca sativa ascorbic acid phenylalanine ammonia-lyase polyphenol oxidase tissue browning

Discrimination of Acacia seeds at species and subspecies levels using an image analyzer

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Forestry Studies in China 2013年第4期15卷 253-260页

作者： V.sivakumar R.ANANDALAKSHMI Rekha R.WARRIER b.G.SINGH M.TIGAbU b.NAGARAJAN Division of Seed Technology Institute of Forest Genetics and Tree Breeding Indian Council of Forestry Research and Education Swedish University of Agricultural Sciences Southern Swedish Forest Research Centre

Seeds of Acacia species and subspecies were characterized using an image analyzer and discriminated for the purpose of identification of species, using their seeds. The species considered in the study were Acacia nilotica subsp. indica, A. nilotica subsp. cupressiformis, A. nilotica subsp. tomentosa, A. tortilis subsp. raddiana, A. tortilis subsp. spirocarpa, A. raddiana, A. senegal, A. auriculiformis, A. farnesiana, A. leucophloea, A. mearnsii, A. melanoxylon, A. planifrons and A. mangium. Eight samples each consisting of 25 seeds per species were studied using the image analyzer for physical characteristics of seeds, such as 2D surface area, length, width, perimeter, roundness, aspect ratio and fullness ratio. Discriminant analysis showed that acacias can be discriminated at species and subspecies levels, with 96% accuracy. Exceptions were A. nilotica subsp. tomentosa(75.0%), A. tortilis subsp. spirocarpa(75.0%) and A. raddiana(87.5%) which had relatively low discrimination accuracy. However, discriminant analysis within selected species showed complete recognition of these species except for A. tortilis subsp. spirocarpa, that had still a large overlap with A. leucophloea. The study also revealed that both seed size and shape characteristics were responsible for species discrimination. It can be concluded that rapid analysis of seed size and shape characteristics using image analysis techniques can be used as primary and secondary keys for identification of acacias.

关键词： Acacia image analyzer discriminant analysis seed identification

Can the Grain-for-Green Program Really Ensure a Low Sediment Load on the Chinese Loess Plateau?

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Engineering 2019年第5期5卷 855-864页

作者： Pengcheng Sun Yiping Wu Zhifeng Yang bellie sivakumar Linjing Qiu Shuguang Liu Yanpeng Cai Department of Earth and Environmental Science School of Human Settlements and Civil EngineeringXi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China School of Civil and Environmental Engineering The University of New South WalesSydneyNSW 2052Australia Department of Land Air and Water ResourcesUniversity of CaliforniaDavisCA 95616USA Department of Civil Engineering Indian Institute of Technology BombayMumbai 400076India National Engineering Laboratory for Applied Technology of Forestry and Ecology in South China Central South University of Forestry and TechnologyChangsha 410004China

The Chinese Loess Plateau is the most seriously eroded area in the world and contributes the vast majority of the sediment that goes into the Yellow *** the 1950s,progressive soil and water conservation measures have been implemented—in particular,large-scale ecological restoration has been ongoing since 1999—resulting in a significant reduction of the sediment ***,the mechanism of the sediment transport dynamics is not fully understood due to multiple and complicated influencing factors including climate change and human activities(e.g.,ecological restoration).A challenging question,then,arises:Is the current low sediment level a“new normal”in this era and in the future?To address this question,we selected a typical loess hilly region where considerable ecological restoration has been implemented,and which is regarded as the site of the first and most representative Grainfor-Green program in the Loess *** investigated the evolution of discharge–sediment relationships in the past decades(1960–2010)and their association with the soil and water conservation measures in this *** results showed that there was a distinct change in the regression parameters of the commonly used annual discharge–sediment regression equation—a continuously increasing trend of parameter b and a decreasing trend of parameter a,accompanying the ecological *** increase in exponent b(i.e.,a steeper slope)implies a potential lower sediment load resulting from low discharge and a potential higher sediment load resulting from large *** finding may question the new normal of a low sediment level and implies the potential risk of a large sediment load during extremely wet years.

关键词： Discharge–sediment relationship Ecological restoration Loess hilly region Sediment load Sediment rating parameters