Maximum Operation Time Research Articles

Degradation of off-gas toluene in continuous pyrite Fenton system

Degradation of off-gas toluene from a toluene reservoir and a soil vapor extraction (SVE) process was investigated in a continuous pyrite Fenton system. The removal of off-gas toluene from the toluene reservoir was >95% by 8h in the pyrite Fenton system, while it was ∼97% by 3h in classic Fenton system and then rapidly decreased to initial level by 8h. Continuous consumption of low Fe(II) concentration dissolved from pyrite surface (0.05–0.11mM) was observed in the pyrite Fenton system, which can lead to the effective and successful removal of the gas-phase toluene due to stable production of OH radical (OH). Inhibitor and spectroscopic test results showed that OH was a dominant radical that degraded gas-phase toluene during the reaction. Off-gas toluene from the SVE process was removed by 96% in the pyrite Fenton system, and remnant toluene from rebounding effect was treated by 99%. Main transformation products from toluene oxidation were benzoic acid (31.4%) and CO2 (38.8%) at 4h, while traces of benzyl alcohol (1.3%) and benzaldehyde (0.7%) were observed. Maximum operation time of continuous pyrite Fenton system was estimated to be 56–61d and its optimal operation time achieving emission standard was 28.9d.

UJI AKTIVITAS ANTIOKSIDAN FRAKSI ETER HASIL HIDROLISIS INFUSA DAUN BINAHONG (Anredera cordifolia (Ten.) Steenis) DENGAN METODE DPPH (1,1-DIPHENIL-2-PICRYLHYDRAZYL)

Antioxidant is compounds which have abilities to inhibit oxidation rate. Anredera cordifolia folium consist of flavonoid which have activities as antioxidant. The purpose of this research was to know antioxidant activity at ether fraction of hydrolysed aquous extract of Binahong folium ( Anredera cordifolia ). Ether fraction was obtained by hydrolysing the infuse Binahong folium ( Anredera cordifolia ) with HCl 2N then fractionated with ether and then evaporated. The antioxidant activity was measured by DPPH method using spectrophotometer. The maximum wavelength and operating time quercetin and samples were 515,0 nm (quersetin) and 514,0 nm (ether fraction), 19-30 minute (quersetin) and 19-29 minute (ether fraction). Scavenging activity test done with the DPPH method (1,1- dyphenyl-2-picrylhydrazyl). The decreasing of DPPH radical solution decreased the absorbant intensity. The percentage of radical scavenging activity was performed as EC50 (Effective Concentration). The results indicated that both samples showed free radical scavenging activity with EC50 value for quercetin (2,702±0,15) µg/ml, and ether fraction of (249,31±9,26) µg/ml. Statistical analysis using Kruskall Wallis method with 95% of confident level followed by Mann Whitney test giving evidence the results between samples and positive control (quercetin) are significantly difference.

Liver retraction using n-butyl-2-cyanoacrylate glue during single-incision laparoscopic upper abdominal surgery

Liver retraction is critical in single-incision laparoscopic upper abdominal surgery. Several techniques have been reported. Some need an additional port, whereas others are complicated and time-consuming. n-Butyl-2-cyanoacrylate (NBCA) glue was applied to bond the left lateral lobe of the liver to the diaphragm in different single-incision laparoscopic upper abdominal procedures. Liver adhesion time and duration of operation were recorded, and preoperative and postoperative liver function tests carried out. All procedures were completed successfully without additional ports or special instruments. The technique provided adequate workspace and a clear view. Mean liver adhesion time was 1·5 min. The maximum operating time was 310 min. Levels of alanine and aspartate aminotransferases were raised on day 1 after surgery but had returned to normal by day 7. Creating adhesion between the left lateral lobe of the liver and the diaphragm using NBCA glue is a simple, safe and effective way of achieving liver retraction in single-incision laparoscopic upper abdominal surgery.

Reliability Measure of a Standby System with Arrival Time of the Server Subject to Maximum Operation and Repair Time

Reliability Measure of a Standby System with Arrival Time of the Server Subject to Maximum Operation and Repair Time

Cost-Benefit Analysis of a Computer System with Priority to Preventive Maintenance over Hardware Repair Subject to Maximum Operation and Repair Times

A computer system is analyzed considering the concept of priority to Preventive Maintenance (PM) over hardware repair subject to maximum operation and repair times. Two-identical units of the computer system have been taken up-one is initially operative and other is kept as spare in cold standby. In each unit, hardware (h/w) and software (s/w) work together and may fail independently from normal mode. There is a single server who visits the system immediately when needed to carry out repair activities. PM of the unit is conducted after a Maximum Operation Time (MOT). If repair of the h/w is not possible up to a maximum repair time, it is replaced by a new one with some replacement time. However, only replacement of the s/w is made giving some replacement time with the new one when s/w fails to execute the program properly. Priority to PM of the unit is given over h/w repair. The failure time of the unit follows negative exponential distribution while the distributions of PM, repair and replacements are taken as arbitrary. To carry out the cost-benefit analysis, expressions for several reliability measures are obtained by using semi-Markov and regenerative point technique. The graphical behaviour of some important performance measures of the system has been examined giving particular values to various parameters and costs.

Reliability modeling of a computer system with preventive maintenance and priority subject to maximum operation and repair times

The main focus of this paper is on the reliability modelling of a computer system considering the concepts of redundancy, preventive maintenance and priority in repair activities. Two identical units of a computer system are taken—one unit is initially operative and the other is kept as spare in cold standby. In each unit h/w and s/w work together and may fail independently from normal mode. There is a single server who visits the system immediately as and when needed. Server conducts preventive maintenance of the unit (computer system) after a maximum operation time. Repair of the h/w is done at its failure while s/w is upgraded from time to time as per requirements. If server unable to repair the h/w in a pre-specific time (called maximum repair time), h/w is replaced by new one giving some replacement time. Priority to h/w repair is given over s/w up gradation if, in one unit s/w is under up-gradation and h/w fails in another operative unit. The failure time of h/w and s/w follows negative exponential distributions while the distributions of preventive maintenance, h/w repair/replacement and s/w up-gradation times are taken as arbitrary with different probability density functions. The expressions for several reliability and economic measures are derived in steady state using semi-Markov process and regenerative point technique. The graphical study of mean time to system failure (MTSF) and profit function has also been made giving particular values to various parameters and costs.

A Novel Tool To Improve the Rate of Penetration–Hydraulic-Pulsed Cavitating-Jet Generator

Summary On the basis of the analysis of the jet-modulating mechanism, a novel tool—a hydraulic-pulsed cavitating-jet generator (HPCJG)— is designed to further improve the rate of penetration (ROP). The HPCJG combines the advantages of a pulsed jet and a cavitating jet. When the drilling fluid flows through this tool, the fluid will be modulated to the pulsed and cavitating jet by application of the impellers and by entering into the self-resonant chamber. During this process, a pulsed cavitating jet is formed at the outlet of the bit nozzle. Because of jet pulsation, cavitating erosion, and the local negative-pressure effect, the cleaning efficiency of the well-bottom cuttings and the ROP will be improved. Laboratory and oilfield tests have indicated that the pulsed-pressure amplitude and the pressure drop of the generator increase with the increase of the flow rate. However, the frequency of the pressure pulsation is invariable in this process. This generator has been applied to more than 100 wells in eight oil fields throughout China. The results show that the maximum density of the test drilling fluid is 1.93 g/cm3, the maximum test-well depth is 6162 m, and the operation time of the generator is more than 230 hours (the maximum operation time recorded was more than 520 hours). Furthermore, the average ROP was increased by approximately 16.7% to 104.4%. In conclusion, the generator has the characteristics of a simple structure, has a long lifetime, is able to adapt well with existing drilling equipment, and can provide a safe and efficient drilling technique for deep wells.

A methodology to solve large-scale cooperative transportation planning problems

In this paper, we suggest a methodology to solve a cooperative transportation planning problem and to assess its performance. The problem is motivated by a real-world scenario found in the German food industry. Several manufacturers with same customers but complementary food products share their vehicle fleets to deliver their customers. After an appropriate decomposition of the entire problem into sub problems, we obtain a set of rich vehicle routing problems (VRPs) with time windows for the delivery of the orders, capacity constraints, maximum operating times for the vehicles, and outsourcing options. Each of the resulting sub problems is solved by a greedy heuristic that takes the distance of the locations of customers and the time window constraints into account. The greedy heuristic is improved by an appropriate Ant Colony System (ACS). The suggested heuristics to solve the problem are assessed within a dynamic and stochastic environment in a rolling horizon setting using discrete event simulation. We describe the used simulation infrastructure. The results of extensive simulation experiments based on randomly generated problem instances and scenarios are provided and discussed. We show that the cooperative setting outperforms the non-cooperative one.

Stochastic Modeling of a Computer System with Priority to PM over S/W Replacement Subject to Maximum Operation and Repair Times

ABSTRACT This paper focuses on the stochastic modeling of a computer system of two identical units- one is initially operative and other is kept as spare in cold standby. In each unit h/w and s/w components work together and fail independently. There is a single server who visits the system immediately as and when required. The server takes the unit under preventive maintenance after a maximum operation time at normal mode. The h/w components under go for repair at their failure and are replaced by new one in case these are not repaired up to a maximum repair time. However, s/w components are replaced by new one instead of repair. Priority is given to the preventive maintenance (PM) of the unit over replacement of the s/w components. The failure time distribution of the components follow negative exponential whereas the distributions of preventive maintenance, repair and replacement time are taken as arbitrary with different probability density functions. Several reliability and economic indices have been obtained using semi-Markov and regenerative point technique. The graphical study of the results has also been made.

Holmium Laser Enucleation Versus Bipolar Resection of the Prostate: A Prospective Randomized Study. Which to Choose?

Holmium enucleation of the prostate (HoLEP) has been established as an effective therapy for patients with benign prostatic hyperplasia (BPH), with less bleeding, shorter catheterization time, and shorter hospital stay. The evolution of the bipolar transurethral resection of the prostate (TURP) raised a question: Would it be able to provide all the advantages of HoLEP and compensate for all its drawbacks, including the higher costs and the steep learning curve? A randomized study was performed that compared HoLEP with bipolar TURP. The study included 60 patients with BPH who were randomized in two groups (1:1 fashion). The mean age, International Prostate Symptom Score, serum prostate-specific antigen value, maximum urinary flow rate, residual urine, prostate size, operative time, blood loss, resected volume, catheterization time, hospital stay, and intraoperative and postoperative complications were compared in both groups, with a follow-up period of 6 months postoperatively. Both techniques were comparable to each other. They shared the same advantages of decreased perioperative morbidity. The longer operative time in the HoLEP group, however, was still statistically significant. In addition, the expense of performing HoLEP was nearly double that of bipolar TURP. HoLEP and bipolar TURP are effective in treating patients with lower urinary tract symptoms due to BPH, however; the long operative time, the steep learning curve, as well as the higher expenses of HoLEP are in favor of bipolar TURP.

SS&IAGA-EM-based Algorithm for Fitting a Continuous PH Distribution

It is an important and difficult task in model analysis of traffic engineering to fit with the general distribution or test data whether which fit the distribution or not via PH distribution. Although there are lots of methods to fit continuous PH distribution, which are all lack of efficiency and numerical stability. For giving consideration to both fitting effect and efficiency of a continuous PH distribution, we apply the maximum likelihood method to the dense subset HErD of PH distribution and design a SS & IAGA-EM algorithm for study. In the data fitting test for long-tailed distribution function, partial peak distribution function and heavy-tailed distribution function with a sample size of 104, the maximum error of the algorithm is 7.32%. When operated in a standard PC with 2.5GHz Pentium CPU running under the operating system of Windows XP, the maximum operating time of the algorithm is 100s, which meets the demand for effectiveness and efficiency.

Nationwide survey on the operational status of electron accelerators for radiation therapy in Japan

A nationwide survey was conducted on electron accelerators for radiation therapy in Japan for obtaining fundamental data on the actual operational situation of these accelerators. The research subjects were all medical institutions equipped with electron accelerators for radiation therapy (874 accelerators) in Japan. Postcards explaining the purpose and procedure of the survey were sent to each institution. Each institution was requested to download a questionnaire from the website and return it by e-mail. We obtained the following results. Energy: about 90% of the accelerators did not exceed 10 MeV as the permitted maximum energy. Beam intensity: a total of 94% of the accelerators did not exceed 4 Gy/min as the mean exposure dose rate. Beam time: a total of 74% of the accelerators were below half of the permitted maximum beam time. However, 2% of the accelerators exceeded 90% of the permitted maximum time. Cumulative dose: about 10% of institutions obtained permission not to use the maximum beam time, but to use the maximum cumulative dose to secure sufficient beam time. From these results, it became clear that the induced radioactivity based on the maximum beam current and the maximum operating time under an official permit would be overestimated. Therefore, the neutron dose should be assessed by use of a daily operational record, not from an official permit.

Nationwide survey on the operational status of medical compact cyclotrons in Japan

The management of induced radioactivity of the cyclotron itself and structures is an important issue in decommissioning of medical compact cyclotrons. To obtain basic data on the actual operational conditions of cyclotrons, we performed nationwide survey. The actual beam current was about half of the maximum beam current indicated in the official permits for cyclotron operation. The actual operating time was about 10% of the maximum operating time indicated in the official permits. The average daily radioactive-nuclide ((18)F) production was only 10% of the allowed maximum quantity. From these results, it became clear that the induced radioactivity of a cyclotron and its concrete structures based on the maximum beam current and the maximum operating time may be overestimated. These basic data are expected to be useful for a realistic evaluation and helpful in establishing a rational regulation in regard to radioactive waste control for decommissioning of medical cyclotrons.

Field Survey of the Emergency Power Supply Related to Business Continuity

With the development of economic globalization, as well as the current industrial structure in which the interruption of business activities would have a worldwide impact, preparations to maintain the operation level of important business tasks in the event of a disaster have become increasingly important in both the public and private sectors. This study focused on the electrical power system in buildings and a field survey was performed on emergency power supply facilities to secure an emergency power supply in the major business districts of Japan. The objective of the study was to extract beneficial information regarding the emergency power supply capacity related to business continuity in buildings located in the central business district, to contribute to the future establishment of BCPs.The results of the analysis indicated that the percentage of the capacity of the emergency power supply in contract demand tends to be larger when running time equivalent to full-load operation is longer on the whole. The survey indicated that in the majority of the buildings, the maximum operating time on the emergency power supply is 24 h or less. Therefore, business continuity will be impossible if the power supply is interrupted for more than 24 h.

A tabu search algorithm for the periodic vehicle routing problem with multiple vehicle trips and accessibility restrictions

In this paper, we consider a periodic vehicle routing problem that includes, in addition to the classical constraints, the possibility of a vehicle doing more than one route per day, as long as the maximum daily operation time for the vehicle is not exceeded. In addition, some constraints relating to accessibility of the vehicles to the customers, in the sense that not every vehicle can visit every customer, must be observed. We refer to the problem we consider here as the site-dependent multi-trip periodic vehicle routing problem. An algorithm based on tabu search is presented for the problem and computational results presented on randomly generated test problems that are made publicly available. Our algorithm is also tested on a number of routing problems from the literature that constitute particular cases of the proposed problem. Specifically we consider the periodic vehicle routing problem; the site-dependent vehicle routing problem; the multi-trip vehicle routing problem; and the classical vehicle routing problem. Computational results for our tabu search algorithm on test problems taken from the literature for all of these problems are presented.

Implementation of the three-qubit phase-flip error correction code with superconducting qubits

We investigate the performance of a three-qubit error correcting code in the framework of superconducting qubit implementations. Such a code can recover a quantum state perfectly in the case of dephasing errors but only in situations where the dephasing rate is low. Numerical studies in previous work have however shown that the code does increase the fidelity of the encoded state even in the presence of high error probability, during both storage and processing. In this work we give analytical expressions for the fidelity of such a code. We consider two specific schemes for qubit-qubit interaction realizable in superconducting systems; one ${\ensuremath{\sigma}}_{z}{\ensuremath{\sigma}}_{z}$ coupling and one cavity-mediated coupling. With these realizations in mind, and considering errors during storing as well as processing, we calculate the maximum operation time allowed in order to still benefit from the code. We show that this limit can be reached with current technology.

Conceptual design modifications of the cooling system of MNSR reactor to increase its maximum continuous operation time

To increase the maximum daily operation time of Miniature Neutron Source Reactor (MNSR) reactor several conceptual thermal hydraulic design modifications have been investigated aiming at the improvement of reactor cooling conditions to limit the increase of average core temperature. For this purpose an integrated full-scale thermal hydraulic-neutronics model using the advanced code ATHLET has been developed, tested and verified. The selected design modifications rely upon introducing auxiliary cooling systems operating in four different modes to cool pool water or reactor water using heat exchanger located either inside or outside of reactor pool. The simulation results show that the increase of continuous reactor operation time varies between 1 and 8 additional operation hours. The optimal results are achieved for the second and the fourth options that use external heat exchanger. The second option enables the extending of continuous operation time up to 10 h and the fourth up to 15 h, both at nominal reactor power and under the assumption of initial excess reactivity corresponding to the fresh reactor core. The analysis included the evaluation of xenon poisoning effect on the increase of operation time. It has been shown that its remarkable effect starts after the first 3 operation hours and increases continuously after that. For the best cooling options, where the average core temperature is being fixed at certain value resulting in complete elimination of reactivity feedback of cooling temperature, xenon effect becomes the exclusive limiting effect during the later operation phase. The analysis discuss also general aspects of technical realization for the different cooling options in relation with the specific features of MNSR and the preliminary engineering safety measures and operational radiological protection that have to be taken. The performed analysis and the achieved results during this work would make valuable contribution for updating the Safety Analysis Report (SAR) of MNSR.

Assessment of cooling effects on extending the maximum operating time for the Syrian miniature neutron source reactor

Various schemes of cooling have been investigated for the purpose of assessing potential benefits on the operational characteristics of the Syrian MNSR reactor. A detailed thermal hydraulic model for the analysis of MNSR has been developed. The analysis shows that an auxiliary cooling system, installed in the pool which surrounds the lower section of the reactor vessel, will significantly offset the consumption of excess reactivity due to the negative reactivity temperature coefficient. Hence, the maximum operating time of the reactor is extended. Compared with experimental data, the suggested model proves to be valid for the analysis of MNSR behavior under both steady state and transient conditions.

Laparoscopic cholecystectomy in empyema of gall bladder: An experience at Liaquat University Hospital, Jamshoro, Pakistan

Objective:To find out the safety profile of laparoscopic cholecystectomy in empyema of gallbladder.Background:Empyema of gall bladder is a severe form of acute cholecystitis with superadded suppuration. It has been considered a contraindication for the laparoscopic cholecystectomy (LC) because of fear of life-threatening complications. This study aimed to determine the safety and feasibility of LC in empyema of gallbladder.Materials and Methods:LC was attempted in 67 patients of empyema of gallbladder within 24h. However in few cases there was a delay because of reluctance for surgery or delay in giving consent etc. The procedure was performed by standard four-port technique with few changes made to facilitate dissection according to situation.Results:Between April 2003 to June 2006, 970 LC performed for gallstone disease at surgical unit-1 of LUMHS by the same surgical team. Among these, 67 (6.90%) patients were diagnosed to have empyema gall bladder. LC successfully completed in 54 (80.59%) patients. In 13 (19.40%) patients the procedure was converted to open cholecystectomy (OC) due to various operative difficulties of which the most serious injuries included bleeding from cystic artery (four cases), common bile duct injury (two cases) and duodenal injury in one case. Maximum operating time was up to 160 minutes (one case). Postoperative complications occurred in 10 (18.51%) successfully operated patients. Maximum patients (n=45, 83.33%) were discharged in 48-96 hours while three patients were discharged after two weeks.Conclusion:Laparoscopic cholecystectomy can be performed in empyema of gallbladder keeping in mind a slightly increased risk of complications even in the best hands. However, the experience of the surgeon plays a key role in the overall outcome.

Model-based heuristic optimized operating policies for d-glucose oxidation in a batch reactor with pulsate addition of enzyme

Model-based optimization of batch enzymatic/bio-reactors is an intensively studied problem due to the increased economic benefits offered by the predicted optimal operating policies. The enzymatic oxidation of d-glucose (DG) in a batch reactor is a process of industrial interest, leading to production of “rare sugars” (keto-derivatives) from monosaccharides. The enzyme activity is sensitive to operating conditions, deactivation occurring due to some of the products and impurities. To keep a high catalytic activity during the batch, a pulsate addition of enzyme solution is performed under some restrictions. By imposing the maximum batch operation time and injected volume, operating policies maximizing the DG-conversion can be derived for every batch case. In the present study, by accounting the process kinetic characteristics, a pulse-injection control function, of exponential type, is proved to be easily adaptable for the optimization of the batch reactor. The heuristic near optimal solution is simple, flexible and can efficiently replace the optimal impulse-fed-policy derived by means of the time-consuming classical direct methods. The heuristic rule, based on the process kinetic model and on a library of semi-empirical functions, can be easily applied to optimize various batch enzymatic processes.