Analysis of classical retrial queue with differentiated vacation and state dependent arrival rate.

In present paper we have introduced the concept of differentiated vacations in a retrial queueing model with state dependent arrival rates of customers. The arrival rate of customers is different in various states of the server. The vacation types are differentiated by means of their durations as well as the previous state of the server. In type I vacation, server goes just after providing service to at least one customer whereas in type II, it comes after remaining free for some time. In steady state, we have obtained the system size probabilities and other system performance measures. Finally, sensitivity and cost analysis of the proposed model is also performed. The probability generating function technique, parabolic method and MATLAB is used for the purpose

Comparative Study of Laparoscopic Cholecystectomy Versus Open Cholecystectomy in Elderly Patients: An Observational Comparative Study

Background: Surgery for cholelithiasis is more common in elderly patients as the incidence of gallstones increases with age. Age is one of the critical factors affecting the mortality and morbidity rates after open cholecystectomy (OC). The aim of this report was to evaluate and comparing the outcome of laparoscopic cholecystectomy (LC) in elderly patients (≥ 65 years old) with that of OC.Methods: A prospective observational comparative study was conducted in the Department of General Surgery at R.G. Kar Medical College and Hospital, India, from January 2012 to June 2013. 50 patients were involved. Group 1 had patients planned for conventional LC, i.e., LC group and Group 2 with OC, i.e., OC group. Patients included were the cases who aged 65 years and above, with symptomatic gallstone disease, with asymptomatic gallstone with associated illnesses or with anticipated complications. Various variables were compared intraoperatively and postoperatively.Results: Significant differences were seen in LC group with more duration of surgery than OC group. The pain score was significantly low in LC group after 6 and 24 hours. The duration of hospital stay was also significantly less in LC group. Pulmonary function tests were done on 1st and 6th post-operative days showed a significant difference of peak expiratory flow rate, forced expiratory volume1, and forced vital capacity between LC and OC on 1st post-operative day.Conclusions: LC should be advised for elderly patients as an elective procedure safely as post-operative morbidity is much less in LC compared to the OC

(R1971) Analysis of Feedback Queueing Model with Differentiated Vacations under Classical Retrial Policy

This paper analyzes an M/M/1 retrial queue under differentiated vacations and Bernoulli feedback policy. On receiving the service, if the customer is not satisfied, then he may join the retrial group again with some probability and demand for service or may leave the system with the complementary probability. Using the probability generating functions technique, the steady-state solutions of the system are obtained. Furthermore, we have obtained some of the important performance measures such as expected orbit length, expected length of the system, sojourn times and probability of server being in different states. Using MATLAB software, we have represented the graphical interpretation of the results obtained. Finally, the cost is optimized using the parabolic method

A note on squeezing function and its generalizations

This note investigates the relation between squeezing function and its generalizations. Using the relation obtained, we present an alternate method to find expression of generalized squeezing function of unit ball corresponding to the generalized complex ellipsoids.Comment: 9 page

Squeezing function corresponding to polydisk

In the present article, we define squeezing function corresponding to polydisk and study its properties. We investigate relationship between squeezing fuction and squeezing function corresponding to polydisk.Comment: Published in Complex Analysis and its Synergie

Squeezing function for dd-balanced domains

We introduce the notion of squeezing function corresponding to $d$-balanced domains motivated by the concept of generalized squeezing function given by Rong and Yang. In this work we study some of its properties and its relation with Fridman invariant.Comment: 11 pages, comments are welcom

Porous ceramics for multistage Knudsen micropumps—modeling approach and experimental evaluation

This paper describes the evaluation of four types of porous ceramics for use as thermal transpiration materials in Knudsen pumps that operate at atmospheric pressure. Knudsen pumps are motionless gas pumps that utilize thermal transpiration along a channel or a set of channels; the channels must have a temperature gradient and must constrain the flow to remain within the free molecular or transitional flow regimes. Of the ceramics evaluated, a clay-based, 15 bar synthetic ceramic (15PC) presents the most favorable properties for Knudsen pumps. For an input power of 3.4 W, a 25 _ 25 mm 2 nine-stage Knudsen pump that uses this material provides a maximum pressure head of 12 kPa and a maximum gas flow rate of ≈3.7 µL min _1 . Reliability tests demonstrate more than 11 750 h of continuous operation without any deterioration in their gas pumping capabilities. A fitted model suggests that the temporal evolution of pressure at the sealed outlet of a Knudsen pump can be captured adequately using four parameters. These parameters correspond to various nonidealities that play dominant roles in the transient response of these pumps.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90805/1/0960-1317_21_9_095029.pd

GREEN BUSINESS- Way to achieve globally sustainable competitive advantage

Green business” refers to sustainable business that meets customers’ needs in ways that solve rather than cause environmental and social problems. Green businesses operate across all business sectors from production of conventional goods/services to developing new breakthrough technologies. This model of socially and environmentally responsible business does not assume sacrificing of corporate profits. On the contrary, sustainable businesses show financial success in long-run, benefit many stakeholders while exploiting none. This paper explores the tremendous impact the green movement is having on marketing and business strategies. It explores the possibilities that green technologies and products have on sustainable competitive advantage in the competitive environment. This paper takes an active approach and proposes to turn business green. Potential benefits of such an action are provided as arguments to support the decision. In this paper, three factors were identified as crucial for achieving a so-called green sustainable competitive advantage: entrepreneurship, commitment to the environment, and corporate social responsibility. As the competitive arena is constantly being shifted by institutions towards ecology through new regulation, utilization of those resources enables firms to better respond to the changes and gain a favorable position in the market. Green business also provides an opportunity to expand through substituting products or by entering new geographical areas

A Motionless Gas Micropump Using Thermal Transpiration in Bulk Nanoporous Materials.

Thermal transpiration-driven Knudsen pumps have the ability to pump gas molecules without the use of any moving parts. This promises high structural reliability and low frictional losses. However, the dearth of suitable transpiration materials with appropriate properties has limited their performance, especially for atmospheric pressure operation. This thesis describes the use of bulk nanoporous materials for thermal transpiration-driven gas pumping at atmospheric pressure. A naturally-occurring zeolite, clinoptilolite, is used to demonstrate the feasibility of thermal transpiration-driven Knudsen pumps using bulk nanoporous ceramics. For an input power of 5.35W, the initial prototype has a temperature bias of 38K across the thickness of the zeolite disc. This results in a gas flow of ≈0.12sccm with a nominal pressure load of ≈50Pa at the output, or a maximum pressure head of ≈1kPa. Transient pressure response at the sealed outlet of a Knudsen pump is analyzed using a fitted model, which allows us to quantify various non-idealities. Several other synthetic nanoporous ceramics are also evaluated for their thermal transpiration-driven gas flow characteristics. A clay-based ceramic 15PC is identified as suitable for multistage Knudsen pumps that may accommodate higher pressure heads. While operating at 55K above room temperature, a 9-stage Knudsen pump is demonstrated to generate a maximum pressure head ≈12kPa, or a gas flow of ≈3.8µL/min. against a pressure head of 160Pa. The pump has a footprint of ≈8x8mm2/stage. To date, a multistage Knudsen pump has operated continuously for more than 7000 hours without any deterioration in its performance. Higher gas flow generation capabilities are demonstrated using thermal transpiration through nanoporous cellulose ester polymer membranes. For an input power of 1.4W, a single stage Knudsen pump with 11.5mm diameter and 105µm thick polymer membrane has a temperature bias of 30K across the membrane, which provides 0.4sccm flow against a 330Pa pressure head. Experiments suggest that the polymer Knudsen pump results in a thermal transpiration-driven gas flow of ≈1 sccm in absence of any external load. It has a final packaged volume of 14x14x4.5mm3. To date, a polymer pump has operated continuously for more than 600 hours without deterioration.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75842/1/gnaveen_1.pd

Non-Clairvoyant Precedence Constrained Scheduling

We consider the online problem of scheduling jobs on identical machines, where jobs have precedence constraints. We are interested in the demanding setting where the jobs sizes are not known up-front, but are revealed only upon completion (the non-clairvoyant setting). Such precedence-constrained scheduling problems routinely arise in map-reduce and large-scale optimization. For minimizing the total weighted completion time, we give a constant-competitive algorithm. And for total weighted flow-time, we give an O(1/epsilon^2)-competitive algorithm under (1+epsilon)-speed augmentation and a natural "no-surprises" assumption on release dates of jobs (which we show is necessary in this context). Our algorithm proceeds by assigning virtual rates to all waiting jobs, including the ones which are dependent on other uncompleted jobs. We then use these virtual rates to decide on the actual rates of minimal jobs (i.e., jobs which do not have dependencies and hence are eligible to run). Interestingly, the virtual rates are obtained by allocating time in a fair manner, using a Eisenberg-Gale-type convex program (which we can solve optimally using a primal-dual scheme). The optimality condition of this convex program allows us to show dual-fitting proofs more easily, without having to guess and hand-craft the duals. This idea of using fair virtual rates may have broader applicability in scheduling problems