Design and Testing of Innovative Rotational Mould Heated by Thermal Fluid

2010 ◽  
Author(s):  
M. D. Monzo´n ◽  
A. N. Beni´tez ◽  
P. Bordo´n ◽  
P. M. Herna´ndez ◽  
M. D. Marrero ◽  
...  
Keyword(s):  
Cycle Time ◽  
Energetic Efficiency ◽  
Internal Stresses ◽  
Cycle Times ◽  
Transfer Processes ◽  
Computational Fluids Dynamics ◽  
Heating And Cooling ◽  
Computational Fluids ◽  
Plastic Parts ◽  
Design And Testing

Rotomoulded plastic parts have no internal stresses, as it is a process carried out at lower temperatures than injection moulding and no pressure is applied. The main disadvantage is the high cycle times needed. This paper focuses on reducing this cycle time and in producing a mould using standardized parts. For cycle time reducing, it is proposed to heat the mould by thermal fluid in continuous circulation; heat transfer processes have been studied for over 20 different configurations of the oil’s inlet – outlet, obtaining acceptable results with a manifold with 25 perforations in the front and rear faces. This configuration has been optimized by computational fluids dynamics, allowing reducing heating and cooling time and improving the energetic efficiency and the uniformity of heating. Design, simulations and testing of a 100 mm3 cube have been carried out in order to produce a standardized mould; this mould consists in some standardized parts and a nickel shell, obtained by rapid prototyping and electroforming process. This shell can be removed from the rest of elements in the mould, allowing thus to obtain parts with any other geometry just by changing the nickel shell. An experimental machine for testing has been developed as well.

Finite Element Model to Predict the Bioconversion Rate of Glucose to Fructose using Escherichia coli K12 for Sugar Production from Date

2015 ◽  
Vol 11 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Maher Trigui ◽  
Karim Gabsi ◽  
Walid Zneti ◽  
Suzelle Barrington ◽  
Ahmed Noureddine Helal
Keyword(s):  
Escherichia Coli ◽  
Induction Time ◽  
Volume Fraction ◽  
Element Model ◽  
Initial Concentration ◽  
Computational Fluids Dynamics ◽  
Date Syrup ◽  
Computational Fluids ◽  
Two Phases ◽  
Inoculum Volume

Abstract In this study, Bioconversion process of glucose to fructose from date syrup using Escherichia coli K12 is modeled using a commercial computational fluids dynamics (CFD) code fluent FLUENT 6.3.23 [8] which we implemented a user-defined functions (UDF) to simulate the interrelationships at play between various phases. A two phases CFD model was developed using an Eulerian – Eulerian approach to calculate the fructose volume fraction produced during time. The bioconversion process was studied as function of three initial concentration of glucose (0.14, 0.242 and 0.463gL–1), three induction time (60, 120 and 180 mn) and three inoculum volume (100, 120 and 150mL). The numerical results are compared with experimental data for bioconversion rate and show good agreement (R2= 0.894). The optimal condition of diffusion was obtained by applying an initial concentration of glucose less than 0.2gL–1 and induction time great than 100 minutes.

Fuzzy-neural-network-based fluctuation smoothing rule for reducing the cycle times of jobs with various priorities in a wafer fabrication plant: A simulation study

2009 ◽  
Vol 223 (8) ◽  
pp. 1033-1043 ◽  
Author(s):  
T Chen
Keyword(s):  
Neural Network ◽  
Cycle Time ◽  
Fuzzy Neural Network ◽  
Optimal Solution ◽  
Wafer Fabrication ◽  
Estimation Accuracy ◽  
Cycle Times ◽  
Fuzzy Neural ◽  
The Difference ◽  
Fluctuation Smoothing

This paper presents a fuzzy-neural-network-based fluctuation smoothing rule to further improve the performance of scheduling jobs with various priorities in a wafer fabrication plant. The fuzzy system is modified from the well-known fluctuation smoothing policy for a mean cycle time (FSMCT) rule with three innovative treatments. First, the remaining cycle time of a job is estimated by applying an existing fuzzy-neural-network-based approach to improve the estimation accuracy. Second, the components of the FSMCT rule are normalized to balance their importance. Finally, the division operator is applied instead of the traditional subtraction operator in order to magnify the difference in the slack and to enhance the responsiveness of the FSMCT rule. To evaluate the effectiveness of the proposed methodology, production simulation is applied to generate some test data. According to the experimental results, the proposed methodology outperforms six existing approaches in the reduction of the average cycle times. In addition, the new rule is shown to be a Pareto optimal solution for scheduling jobs in a semiconductor manufacturing plant.

A Head-to-Head Comparison of Hydrogen Peroxide Vapor and Aerosol Room Decontamination Systems

2011 ◽  
Vol 32 (9) ◽  
pp. 831-836 ◽  
Author(s):  
T. Holmdahl ◽  
P. Lanbeck ◽  
M. Wullt ◽  
M. H. Walder
Keyword(s):  
Hydrogen Peroxide ◽  
Cycle Time ◽  
New Technologies ◽  
Biological Indicators ◽  
The Other ◽  
Test Room ◽  
Cycle Times ◽  
Hydrogen Peroxide Vapor ◽  
In Vitro Comparison

Objective.New technologies have emerged in recent years for the disinfection of hospital rooms and equipment that may not be disinfected adequately using conventional methods. There are several hydrogen peroxide–based area decontamination technologies on the market, but no head-to-head studies have been performed.Design.We conducted a head-to-head in vitro comparison of a hydrogen peroxide vapor (HPV) system (Bioquell) and an aerosolized hydrogen peroxide (aHP) system (Sterinis).Setting.The tests were conducted in a purpose-built 136-m3test room.Methods.One HPV generator and 2 aHP machines were used, following recommendations of the manufacturers. Three repeated tests were performed for each system. The microbiological efficacy of the 2 systems was tested using 6-log Tyvek-pouchedGeobacillus stearo-thermophilusbiological indicators (BIs). The indicators were placed at 20 locations in the first test and 14 locations in the subsequent 2 tests for each system.Results.All BIs were inactivated for the 3 HPV tests, compared with only 10% in the first aHP test and 79% in the other 2 aHP tests. The peak hydrogen peroxide concentration was 338 ppm for HPV and 160 ppm for aHP. The total cycle time (including aeration) was 3 and 3.5 hours for the 3 HPV tests and the 3 aHP tests, respectively. Monitoring around the perimeter of the enclosure with a handheld sensor during tests of both systems did not identify leakage.Conclusion.One HPV generator was more effective than 2 aHP machines for the inactivation ofG. stearothermophilusBIs, and cycle times were faster for the HPV system.

scholarly journals SIMULASI DISTRIBUSI TEMPERATUR DAN KELEMBABAN RELATIF RUANGAN DARI SISTEM DEHUMIDIFIKASI MENGGUNAKAN COMPUTATIONAL FLUIDS DYNAMICS (CFD)

ROTASI ◽  
2017 ◽  
Vol 19 (1) ◽  
pp. 1
Author(s):  
Eflita Yohana ◽  
Bambang Yunianto ◽  
Ade Eva Diana
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Simulation ◽  
Liquid Desiccant ◽  
Humidity Ratio ◽  
Computational Fluids Dynamics ◽  
Computational Fluids ◽  
Computational Fluid Dynamics Cfd

Dehumidifikasi merupakan proses pengurangan kadar uap air  yang berpengaruh terhadap besar nilai kelembaban relatif dan temperatur suatu ruangan. Dalam mengkondisikan kadar uap air dalam suatu ruangan tersebut agar dapat sesuai dengan kebutuhan, maka perlu diketahui distribusi kelembaban relatif dan temperatur dalam ruangan menggunakan Computational Fluid Dynamics (CFD). Pada penelitian ini, pengambilan data dilakukan selama 20 menit dan dilakukan pada pukul 08.00 WIB.  Liquid desiccant yang digunakan dijaga pada temperatur 10°C dengan variasi konsentrasi 40% dan 50%. Sensor DHT 11 dipasang pada lima sisi, atap, dinding, lantai, inlet, outlet, yang berfungsi untuk mencatat perubahan kelembaban dan temperatur selama pengujian berlangsung. Pada kondisi normal tanpa menyalakan alat dehumidifier, sensor mencatat temperatur rata-rata di dalam ruangan sebesar 29,9°C dan RH 58,9%. Simulasi dilakukan menggunakan software CFD Solidworks Flow Simulation 2014. Validasi hasil eksperimen dengan hasil simulasi dengan membandingan bahwa liquid desiccant 40% dan 50%, nozzle sprayer 0.2 mm dengan temperatur yang dijaga pada 10°C mempunyai distribusi yang cukup merata dengan konsentrasi 40% memiliki nilai RH terendah sebesar 65,21%, nilai RH tertinggi sebesar 68,99%, nilai ω = 18 gr/kg, serta mempunyai temperatur tertinggi 31,11°C dan temperatur terendah 30,05°C. Sedangkan dengan konsentrasi 50% distribusi dalam ruangan juga cukup merata karena memiliki nilai RH terendah sebesar 59,21%., nilai RH tertinggi sebesar 62,80%, nilai ω = 17 gr/kg, serta mempunyai temperatur tertinggi 31,71°C dan temperatur terendah 30,93°C. Sehingga liquid desiccant dengan konsentrasi 50% mempunyai nilai Humidity Ratio (ω) lebih rendah dibandingkan dengan yang memiliki konsentrasi 40%.

The effect of pressure variations on the formation of gas inclusions in the rotational molding process

2015 ◽  
Vol 35 (5) ◽  
pp. 481-491 ◽  
Author(s):  
Martin Löhner ◽  
Dietmar Drummer
Keyword(s):  
Cycle Time ◽  
Polymer Melt ◽  
Low Pressure ◽  
Rotational Molding ◽  
Molding Process ◽  
Inclusion Removal ◽  
Heating And Cooling ◽  
Polymer Powder ◽  
Major Disadvantage ◽  
Plastic Processing

Abstract The major disadvantage of rotational molding is the cycle time, which is very long compared to other plastic processing methods. A major percentage of the cycle time besides heating and cooling results from the time necessary to remove gas inclusions from the polymer melt, which are trapped while sintering the polymer powder. In this work the formation of gas inclusions is investigated by conducting a cycle time variation on a uniaxial rotational molding machine. The influence of low pressure during melting on the formation of inclusions is investigated by examining sintering experiments with a pressure variation during the melting of the polymer. Sintering experiments are conducted with different melt residence times to investigate the mechanisms of gas inclusion removal. By comparing the time to reach a pore-free polymeric melt, the cycle time reduction potential under low-pressure application while melting the polymeric powder is estimated.

Study of the Gas Combustion LP in an Atmospheric Burner

2008 ◽  
Author(s):  
Armando Gallegos-Mun˜oz ◽  
Armando Balderas-Bernal ◽  
Alejandro Rami´rez-Barro´n ◽  
J. C. Prince-Avelino
Keyword(s):  
Fluid Dynamic ◽  
Premixed Combustion ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Finite Rate ◽  
Gas Combustion ◽  
Finite Speed ◽  
Computational Fluids Dynamics ◽  
Computational Fluids ◽  
Laminar Flamelet

The study of the gas combustion LP in an atmospheric burner to bake ceramics is presented. The study includes different models from combustion and turbulence to find the best interaction chemistry-turbulence, applying Computational Fluids Dynamics (CFD) through FLUENT®. For the study different models of combustion were considered, where the finite speed of the reaction is important by means of kinetic chemistry from Arrhenius. The different models of combustion were; a generalized model of speed of Finite Rate/Eddy dissipation, non-premixed combustion Laminar Flamelet and Eddy dissipation. Each one of these models represents the combustion non-premixed of gas LP, to simulate the combustion of turbulent diffusive flames. For the study of the turbulence the model k-epsilon was applied. The results obtained for each combination turbulence-chemistry were compared with experimental measurements of temperature within the furnace. This comparison allowed making adjustments in the modeling of the process of combustion, identifying the best interaction between combustion and turbulence. According to the obtained results, the k-epsilon model represents adequately the fluid-dynamic development of the flame within the furnace. The models of combustion Finite Rate/Eddy dissipation and Laminar Flamelet show the best approach to the experimental results, where the k-epsilon model is applied to modeling the turbulence-chemistry interaction.

scholarly journals Administrative Preparedness Strategies: Expediting Procurement and Contracting Cycle Times During an Emergency

2017 ◽  
Vol 132 (3) ◽  
pp. 294-297
Author(s):  
David Hurst ◽  
Sharon Sharpe ◽  
Valerie A. Yeager
Keyword(s):  
Public Health ◽  
Cycle Time ◽  
Emergency Preparedness ◽  
Public Health Emergency ◽  
Open Market ◽  
Cycle Times ◽  
Goods And Services ◽  
Cooperative Agreements ◽  
Hospital Preparedness ◽  
Cooperative Purchasing

We assessed whether administrative preparedness processes that were intended to expedite the acquisition of goods and services during a public health emergency affect estimated procurement and contracting cycle times. We obtained data from 2014-2015 applications to the Hospital Preparedness Program and Public Health Emergency Preparedness (HPP-PHEP) cooperative agreements. We compared the estimated procurement and contracting cycle times of 61 HPP-PHEP awardees that did and did not have certain administrative processes in place. Certain processes, such as statutes allowing for procuring and contracting on the open market, had an effect on reducing the estimated cycle times for obtaining goods and services. Other processes, such as cooperative purchasing agreements, also had an effect on estimated procurement time. For example, awardees with statutes that permitted them to obtain goods and services in the open market had an average procurement cycle time of 6 days; those without such statutes had a cycle time of 17 days ( P = .04). PHEP awardees should consider adopting these or similar processes in an effort to reduce cycle times.

Seven Q-Tracks Monitors of Laboratory Quality Drive General Performance Improvement: Experience From the College of American Pathologists Q-Tracks Program 1999–2011

2015 ◽  
Vol 139 (6) ◽  
pp. 762-775 ◽  
Author(s):  
Frederick A. Meier ◽  
Rhona J. Souers ◽  
Peter J. Howanitz ◽  
Joseph A. Tworek ◽  
Peter L. Perrotta ◽  
...  
Keyword(s):  
Cycle Time ◽  
Laboratory Testing ◽  
Clinical Laboratory ◽  
Monitoring Program ◽  
Annual Reports ◽  
Cycle Duration ◽  
Cycle Times ◽  
Report Turnaround Time ◽  
Clinical Laboratory Testing ◽  
Over Time

Context Many production systems employ standardized statistical monitors that measure defect rates and cycle times, as indices of performance quality. Clinical laboratory testing, a system that produces test results, is amenable to such monitoring. Objective To demonstrate patterns in clinical laboratory testing defect rates and cycle time using 7 College of American Pathologists Q-Tracks program monitors. Design Subscribers measured monthly rates of outpatient order-entry errors, identification band defects, and specimen rejections; median troponin order-to-report cycle times and rates of STAT test receipt-to-report turnaround time outliers; and critical values reporting event defects, and corrected reports. From these submissions Q-Tracks program staff produced quarterly and annual reports. These charted each subscriber's performance relative to other participating laboratories and aggregate and subgroup performance over time, dividing participants into best and median performers and performers with the most room to improve. Each monitor's patterns of change present percentile distributions of subscribers' performance in relation to monitoring durations and numbers of participating subscribers. Changes over time in defect frequencies and the cycle duration quantify effects on performance of monitor participation. Results All monitors showed significant decreases in defect rates as the 7 monitors ran variously for 6, 6, 7, 11, 12, 13, and 13 years. The most striking decreases occurred among performers who initially had the most room to improve and among subscribers who participated the longest. All 7 monitors registered significant improvement. Participation effects improved between 0.85% and 5.1% per quarter of participation. Conclusions Using statistical quality measures, collecting data monthly, and receiving reports quarterly and yearly, subscribers to a comparative monitoring program documented significant decreases in defect rates and shortening of a cycle time for 6 to 13 years in all 7 ongoing clinical laboratory quality monitors.

An expert assistant for selecting green splits, cycle times, and phasing schemes based on the Canadian Capacity Guide procedures

1992 ◽  
Vol 19 (2) ◽  
pp. 245-251 ◽  
Author(s):  
J. Allen Stewart ◽  
Michel Van Aerde
Keyword(s):  
Key Words ◽  
Cycle Time ◽  
Traffic Signal ◽  
Optimization Process ◽  
Signal Timing ◽  
Cycle Times ◽  
Ultimate Outcome

The determination of the optimum phase scheme, cycle time, and green split for an isolated traffic signal is usually a very tedious and time-consuming activity. Several computer packages, such as the Micro-Sintral program, have been developed to assist in such situations by automating many of the calculations for a given set of inputs. Unfortunately, the inputs are often equally difficult to determine, and as they may depend upon the ultimate outcome of the optimization process, several time-consuming iterations, during which new input values must be calculated, are required. This paper presents a program called Signal Expert which automates the above iterations and therefore greatly reduces the traffic engineer's efforts in generating a new signal timing plan based on the rather sophisticated procedures that are outlined in the Canadian Capacity Guide. The benefits of applying this new program are illustrated and discussed using the example intersections that are analyzed in the Canadian Capacity Guide and in the Micro-Sintral User's Manual. Key words: isolated intersections, capacity, delay.

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