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Priority Queueing System with a Single Server Serving Two Queues M[X1],M[X2]/G1,G2/1 with Balking and Optional Server Vacation
Get PDFIn this paper we study a vacation queueing system with a single server simultaneously dealing with an M[x1] /G1/1 and an M[x2] /G2/1 queues. Two classes of units, priority and non-priority, arrive at the system in two independent compound Poisson streams. Under a non-preemptive priority rule, the server provides a general service to the priority and non-priority units. We further assume that the server may take a vacation of random length just after serving the last customer in the priority unit present in the system. If the server is busy or on vacation, an arriving non-priority customer either join the queue with probability b or balks(does not join the queue) with probability (1 - b). The time dependent probability generating functions have been obtained in terms of their Laplace transforms and the corresponding steady state results are obtained explicitly. Also the average number of customer in the priority and the non-priority queue and the average waiting time are derived. Numerical results are computed
Applications of Composite Convolution Operators
Get PDFThe Composite Convolution Operator is an operator which is obtained by composing Convolution operator with Composition operator. Volterra composite convolution operator is a composition of Volterra convolution operator and Composition operator. The Composite Convolution Operators and Composite Convolution Volterra operators have been defined by using the Expectation operator and Radon-Nikodym derivative. In this paper an attempt has been made to investigate applications of Composite Convolution Operators (CCO) in Integral Convolution Type Equations (ICTE). The study may explore a new technique to solve Fredholm Convolution type integral equations and Volterra Convolution type integral equations. Some methods for solving integral convolution type equations by using Composite Convolution Operators have also been studied. For integral convolution type equations, theorems on existence, uniqueness and estimates for solution have also been proved without any restriction for the parameter. In order to determine the solution by the method of successive approximations in this paper, I have made use of the concept of the Resolvent Kernel to obtain Neumann Series. The Banach Contraction Principle has also been used to obtain some results. The method of Variational Iteration has been applied to find out the approximate solution of integral equations by using Composite Convolution Operators. In this paper Numerical Methods have also been adopted for solution of these integral equations. Fourier transform has been used to solve Integral convolution type equations and Laplace transform has been applied to solve Volterra convolution type equations
A multi-satellite approach for water storage monitoring in an arid watershed
No full textThe objective of this study was to use satellite imagery to monitor the water budget of Al Ain region in the United Arab Emirates (UAE). Inflows and outflows were estimated and the trend of water storage variation in the study area was examined from 2005 to 2014. Evapotranspiration was estimated using the simplified Penman-Monteith equation. Landsat images were used to determine the extent of agricultural and green areas. Time series of gravity recovery and climate experiment (GRACE) observations over the study area were used to assess the inferred water storage variation from satellite data. The change of storage inferred from the Water Budget Equation showed a decreasing trend at an average rate of 2.57 Mm3 annually. Moreover, GRACE readings showed a decreasing trend at a rate of 0.35 cm of water depth annually. Mann-Kendal, a non-parametric trend test, proved the presence of significant negative trends in both time series at a 5% significance level. A two-month lag resulted in a better agreement (R2 = 0.55) between the change in water storage and GRACE anomalies within the study area. These results suggest that water storage in the study area is being depleted significantly. Moreover, the potential of remote sensing in water resource management, especially in remote and arid areas, was demonstrated
Irrigation water requirements for seed corn and coffee under potential climate change scenarios
No full textThe impact of potential future climate change scenarios on the irrigation water requirements (IRRs) of two major agricultural crops (coffee and seed corn) in Hawai\u27i was studied using the Irrigation Management System (IManSys) model. In addition to IRRs calculations, IManSys calculates runoff, deep percolation, canopy interception, and effective rainfall based on plant growth parameters, site specific soil hydrological properties, irrigation system efficiency, and long-term daily weather data. Irrigation water requirements of two crops were simulated using historical climate data and different levels of atmospheric CO2 (330, 550, 710 and 970 ppm), temperature (+1.1 and +6.4 °C) and precipitation (±5, ±10 and ±20%) chosen based on the Intergovernmental Panel on Climate Change (IPCC) AR4 projections under reference, B1, A1B1 and A1F1 emission scenarios. IRRs decreased as CO2emission increased. The average percentage decrease in IRRs for seed corn is higher than that of coffee. However, runoff, rain canopy interception, and deep percolation below the root zone increased as precipitation increased. Canopy interception and drainage increased with increased CO2emission. Evapotranspiration responded positively to air temperature rise, and as a result, IRRs increased as well. Further studies using crop models will predict crop yield responses to these different irrigation scenarios
Asset replacement under improving operating and capital costs: A practical approach
No full textWe analyse the serial asset replacement problem under incomplete data about technological change that that affects the capital cost, operating cost and salvage value of newer assets. We construct an efficient discrete-time algorithm for this problem in the case where only partial information is available about future costs of new assets. The algorithm is based on introducing a corrected annual capital recovery factor into the classic Economic Life method. It produces the same lifetime of the first asset as the benchmark infinite-horizon cost minimisation when the operating cost, capital cost and salvage value of new assets decrease proportionally. The algorithm has the same complexity as the Economic Life method but performs much better under improving technology. Numeric simulation demonstrates a superior efficiency of the suggested algorithm vs. existing methods in practical situations when only few discrete measurements of technological change are available
Analysis and control of genetic regulatory systems with switched drug inputs
No full textBecause cancer usually involves multiple genes and pathways, combination therapy is considered as a promising approach for cancer treatment. However, when multiple drugs are taken by a patient simultaneously, toxicity becomes a concern. A potential solution is to give the drugs sequentially rather than simultaneously. In this study, we try to explore the feasibility of such an approach. Specifically, this study investigates the response of genetic regulatory networks to sequential (switched) drug inputs. The switching mechanism is based on the combination of a state-dependent and time-driven switching function. The design of the switching strategy ensures that the genetic regulatory network will be stabilized and satisfies a decay rate performance index. Simulation results using a mTOR pathway model show the effectiveness of the proposed method
Cow size and age as economic drivers of beef production systems in the Nebraska Sandhills
No full textContribution of cow age and size to profitability of beef production systems in the Nebraska Sandhills was analyzed using hedonic methodology. Four years of cow-calf production systems data from 197 observations per year were used. Historical prices for inputs and production outputs were used. Pooled hedonic type regression models, representing 9 possible production system scenarios, evaluated the effect of cow size and age on profitability. Each model included production year, marketing year, calving season, calf BW at birth, calf weaning age, calf BW at weaning, average cow BW, cow age, wintering system, calf sex, and postweaning system as independent variables. Three variables—(1) calf BW at birth, (2) calf BW at weaning, and (3) calf weaning age—were used as dependent variables in 3 secondary regressions. The secondary estimated effects were added to the primary estimated effects providing an adjusted estimate of cow characteristics on net returns. In general, animals marketed at slaughter contribute more positively to profit if they are from heavier cows. Conversely, if animals are sold at weaning or as yearlings, calves born to the lightest dams contribute most to returns. Dam age also contributes to returns differentially depending on marketing scheme. Younger dams contribute more to profit if cattle are marketed on a hot carcass basis, whereas grid pricing favors contribution to returns of more mature dams. If profit is the motive, the contribution cow size and age make on profitability may or may not be worth considering depending on both production and marketing scheme
Enhancing extension and research activities through the use of web GIS
No full textThere have been numerous efforts aimed at improving geographic literacy in order to address societal challenges. Extension educators can use geographic information system (GIS) technology to help their clients cultivate spatial thinking skills and solve problems. Researchers can use it to model relationships and better answer questions. A program at Prairie View A&M University involves the use of virtual, field, and story map activities associated with Web GIS (online mapping) to expose participants to plant species identification and engage them in spatial thinking. We describe that program and demonstrate the utility of Web GIS as a tool for integrating experiential learning in agro-environmental sciences
Cellulose acetate electrospun nanofibrous membrane: Fabrication, characterization, drug loading and antibacterial properties
No full textCellulose-based materials are one of the most commonly used materials for biomedical applications, which normally applied as carriers for pharmaceuticals and drug-releasing scaffolds. In this study, cellulose acetate (CA) was used to fabricate the nanofibrous membrane using the electrospinning technique. CA solutions at different concentrations were prepared by dissolving the polymer in a mixture of acetic acid/acetone solvents with the ratio of 3: 1. The field emission scanning electron microscope results showed that electrospinning of 10% (w/v) CA produced nanofibres with many beads. When the CA concentration was increased to 14% (w/v), bead-free nanofibres were produced. The contact angle measurement results confirmed the hydrophilic properties of nanofibres. In order to prevent common bacterial infections, a model drug, Tetracycline • HCL was incorporated into the CA nanofibres. The drug-loaded CA nanofibres showed antibacterial activity against Gram-positive and Gram-negative bacteria. CA nanofibres had high water uptake properties. The CA nanofibrous membrane was non-toxic to human skin fibroblast cells. Thus the CA nanofibres with 14% (w/v) concentration exerted suitable properties for wound healing application
Conductive PEDOT:PSS coated polylactide (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) electrospun membranes: Fabrication and characterization
No full textIn the current study, electrospinning technique was used to fabricate composite membranes by blending of a synthetic polymer, polylactic acid (PLA) and a natural polymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV. Conductive membranes were prepared by dipping PLA/PHBV electrospun membranes into poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) solution, which is a biocompatible polymer. The coated and uncoated membranes were evaluated using several techniques. The electrical conductivity of the coated membranes was measured using a digital multimeter. In vitro cell cytotoxicity and cell viability were measured by culturing human skin fibroblast (HSF) cells onto the membranes using MTT assays. It was observed that electrospinning of 20% (w/v) PLA/PHBV with a weight ratio of 50:50 produced the most uniform fibers with no beads. It was observed that the wettability and surface roughness of the PEDOT:PSS coated PLA/PHBV membranes were greatly increased than uncoated membrane. The results of cell viability using MTT assay, cell attachment and cell proliferation showed that the conductive PEDOT:PSS coated PLA/PHBV membrane were more favorable for tissue engineering application than their uncoated counterparts