Investigation of Numerical Conditions of Moving Particle Semi-implicit for Two-Dimensional Wedge Slamming

The sensitivity of moving particle semi-implicit (MPS) simulations to numerical parameters is investigated in this study. Although the verification and validation (V&V) are important to ensure accurate numerical results, the MPS has poor performance in convergences with a time step size. Therefore, users of the MPS need to tune numerical parameters to fit results into benchmarks. However, such tuning parameters are not always valid for other simulations. We propose a practical numerical condition for the MPS simulation of a two-dimensional wedge slamming problem (i.e., an MPS-slamming condition). The MPS-slamming condition is represented by an MPS-slamming number, which provides the optimum time step size once the MPS-slamming number, slamming velocity, deadrise angle of the wedge, and particle size are decided. The simulation study shows that the MPS results can be characterized by the proposed MPS-slamming condition, and the use of the same MPS-slamming number provides a similar flow.

A report on characterization of submerged fermentation of Phellinus linteus in Vietnam

Phellinus linteus strain GC was cultured for harvesting biomass by submerged fermentation method in 100 L fermenter which produced in Vietnam. The process of cultivation of this fungus was performed in aerobic conditions with aeration at 1 vvm, stirred at 150 rpm, temperature from 27oC to 29oC. The observation of cultivation was performed to evaluate the optimum time of growth which produce highest biomass of the mycelium for application purpose of using as functional food. The pH of medium was slightly changed with decrease then increase again, and reached about 6.0 when cultivation process ends. The biomass of mycelium was gradually increased until about 11 days of cultivation with about 30 g/L of dried biomass and the content of of sugar reduced in medium decreased from 40 g/L to 6 g/L.

Study of tofu wastewater treatment using anaerobic baffled reactor: laboratory scale

One of the foods favorites by Indonesian people is tofu. In the process of making tofu, it produces wastewater. The tofu wastewater must be treated first to reduce environmental pollution. To treat the liquid waste, it is using biological treatment by an anaerobic baffled reactor with bio-ball. The purpose of this study was to determine the optimum time at 75% tofu wastewater concentration. The detention time used in this study was 12 hours, 24 hours, 36 hours and 48 hours. Seeding takes time about 45 days, with the obtained VSS was 5550 mg/L. Furthermore, acclimatization in the reactor takes about 30 days, with an efficiency of removing COD of 86.3%. The results obtained that at 12 hours of detention, there is a COD allowance of 79.8%, 24 hours of detention time there is a COD allowance of 85.4%, 36 hours of detention time 86.3%, and 48 hours of detention time 88.4 %. It shows that the optimum detention time in this anaerobic reactor is 48 hours. However, the COD level was 765.3 mg/L is still slightly above the quality standard according to the Minister of Environment Regulation No.5 2014, which is the maximum COD level of 300 mg/L.

Curing characteristics and rheological properties of bentonite- filled rubber blends

The study deals with the examination of the rheological behaviour of rubber blends which were filled with bentonite. The filler - polymer as well as the filler - filler interactions were studied and determined from the frequency sweep and strain sweep rheological measurements. The used natural bentonite was extracted from the locality called Jelsovy Potok. The natural bentonite had a fine fraction with a particle size of 15μm a 45 μm and it was added into rubber blends as a partial replacement of commonly used filler. The rubber blends were characterised on the basis of curing characteristics (minimum torque ML, maximum torque MH, optimum time of cure t(c90), processing safety of blend ts,). Moreover, the complex viscosity and Payne effect were also specified. The required measurements were done by using PRPA 2000.

BRIKET BIOMASSA DARI JERAMI PADI, SAMPAH DAUN DAN KOTORAN SAPI

Indonesia memiliki banyak limbah pertanian yang selama ini hanya dibiarkan atau dibakar begitu saja. Limbah pertanian yang merupakan biomassa mengandung selulosa cukup tinggi dapat digunakan sebagai sumber energi terbarukan berupa briket. Penelitian ini bertujuan untuk mengetahui karakteristik briket yang dibuat dari jerami padi, sampah daun dan kotoran sapi untuk dibandingkan dengan standar briket arang. Dalam penelitian ini dibuat briket dari bahan jerami padi, sampah daun dan kotoran sapi. Pembuatan briket biomassa dilakukan dengan teknik karbonisasi di dalam drum yang tertutup. Arang yang diperolah dihaluskan dan diayak 50 mesh selanjutnya ditambah bahan perekat berupa tapioka dengan perbandingan 7:1 dan sedikit air kemudian dicetak secara manual. Setelah dicetak, briket arang yang diperoleh dijemur dibawah sinar matahari selama 3 hari. Waktu terbentuknya arang dari berbagai jenis biomassa berbeda-beda, waktu optimum untuk bahan dari jerami padi 30 menit, sampah daun 60 menit dan 75 menit untuk kotoran sapi dengan rendemen masing-masing 24,39%, 29,03%, dan 26,26%. Briket yang dihasilkan dari biomassa jerami padi memiliki kadar air 5,9% kadar abu 8,02%, kadar zat mudah menguap 35,68%, kadar karbon terikat 37,48% dan nilai kalor 3000 kal/gr. Briket dari sampah daun memiliki kadar air 5,6%, kadar abu 8,02%, kadar zat mudah menguap 32,46%, kadar karbon terikat 40,55% dan nilai kalor 4600 kal/gr. Briket dari kotoran sapi memiliki kadar air 8,4%, kadar abu 8,32%, kadar zat mudah menguap 26,63%, kadar karbon terikat 50,66% dan nilai kalor 5200 kal/gr. Kata kunci: briket, jerami padi, kotoran sapi,nilai kalor, sampah daun. AbstractIndonesia has a lot of agricultural waste that has been left or burned. Agricultural waste containing high cellulose which to be used as a renewable energy source in the form of briquettes. This study aims to find out the characteristics of briquettes made from rice straw, leaf litter and cow dung to be compared to standard charcoal briquettes. In this study made briquettes from rice straw, leaf waste and cow dung. The manufacture of biomass briquettes was done by carbonization in a closed drum. The charcoal reduced in size in 50 mesh added tapioca adhesive in ratio of 7: 1 and a little water then formed to be briquettes manually. The charcoal briquettes obtained are dried in the sun for 3 days. The time for formation of charcoal from various types of biomass were varies, the optimum time for rice straw was 30 minutes, leaf waste was 60 minutes and 75 minutes for cow dung with yields of charcoal of rice straw was 24.39%, 29.03% for leaf waste and cow dung was 26.26%. Briquettes produced from biomass of rice straw have a water content of 5.9% ash content of 8.02%, a volatile substance content of 35.68%, a carbon-bound content of 37.48% and a heat value of 3000 cal/gr. Briquettes from leaf litter have a water content of 5.6%, ash content of 8.02%, a volatile substance content of 32.46%, a carbon-bound content of 40.55% and a heat value of 4600 cal/gr. Briquettes from cow dung have a water content of 8.4%, ash content of 8.32%, a volatile substance content of 26.63%, a carbon-bound content of 50.66% and a heat value of 5200 cal/gr. Keywords: briquettes, cow dung, heat value, leaf litter rice straw..

The timing of laparoscopic cholecystectomy and nano-ligation clip for acute calculous cholecystitis under guidance of Tokyo guidelines 2018 (multi-center retrospective analysis)

Laparoscopic cholecystectomy (LC) has been recognized as the standard surgical method for cholecystectomy. A nano-absorbable ligation clip. The material used in the ligation clip is composed of basic materials (poly(p-dioxanone), poly trimethylene carbonate or polycaprolactone) and nano-short fibers (Polyglycolide acid or polylactide). The short nano-fibers maintain the crystalline form evenly dispersed in the base material. The diameter of short nano-fibers is 300–500 nm and the length is 20–50 µm. The nano-absorbable ligation clip has strong closing force and will not cause closure failure. However, there are still some controversies about the optimum time for LC treatment of acute calculous cholecystitis (ACC) patients, and the optimum time for performing LC based on evidence-based medicine has not been unanimously recognized. Here, we explore LC timing for ACC treatment under the guidance of the Tokyo Guidelines for Acute Cholecystitis 2018 (TG18). We retrospectively analyzed the data of 3,147 ACC cases undergoing LC in eight hospitals in China. According to the time from the onset of the patient’s symptoms to the operation, they were divided into the following three groups: Group A (onset to operation time of ≤3 days), Group B (onset to operation time of 4–7 days), and Group C (onset to operation time of >7 days). There was no obvious statistical difference in preoperative indicators, such as gender ratio, history of hypertension, diabetes, and abdominal operation; ASA Classification; and TG18 Classification between the three groups. Similarly, the results of preoperative laboratory indices (e.g., white blood cell, C-reactive protein, procalcitonin, platelet, serum creatinine, and international normalized ratio) showed no obvious statistical difference between the three groups. The comparison of gallbladder characteristics under B-ultrasound showed no significant statistical difference between the three groups. However, the conversion rate in Group C was significantly higher than that in Groups A and B, the incidence of complications (e.g., bile leakage, bile duct injury, and wound infection) was significantly higher in Group C than that in Groups A and B, and the postoperative hospital stay was significantly shorter in Group A than that in Groups B and C. A comprehensive analysis of patients’ medical records in multiple medical centers confirms that it is safe and feasible to perform early LC 7 days before the onset of ACC, which can significantly decrease postoperative complications and shorten the postoperative hospital stay for ACC patients. Performing early LC for ACC patients under the TG18 guidelines is safe and feasible. Additionally, since TG18 has obvious practicability and guidance for the clinical practice of hepatobiliary surgery, it is worthy of popularization and application in China.

Pemanfaatan Asap Cair Hasil Pirolisis Batubara sebagai Pestisida Organik pada Rayap (Coptotermes curvignathus Holmgren)

Pyrolysis is a process of chemical decomposition of materials through a heating method in the absence of oxygen or a little oxygen. The utilizing coal as a raw material for making liquid smoke, it is hoped that it will be able to produce pesticides that have economic value and can be used as a termite exterminator. The use of coal as a raw material for making liquid smoke is expected to produce pesticides that have economic value and can be used as a termite repellent. This research aimed to determine the optimum concentration and time of liquid coal smoke as a pesticide against termite insect mortality (Coptotermes curvignathus Holmgren). The method used is the coal pyrolysis process at a temperature of 300 0C. The process of testing the mortality of termites with time and concentration variables. The determination of the liquid smoke content of coal is carried out by qualitative and quantitative analysis. The results showed that the optimum time for termite mortality was 25 minutes with an optimum concentration of 80%, where the termite mortality was obtained by 100%. Based on the results of UV/VIS Spectrophotometer Analysis, the sulfur content of liquid coal smoke was 46.92 mg/kg, and the degree of acidity (pH) was 3.00. The acidity content is high enough to allow pesticides from liquid coal smoke to be widely used in agriculture.

Evaluation of Optimal Occasional Tilt on Photovoltaic Power Plant Energy Efficiency and Land Use Requirements, Iran

The paper studies the optimum panel horizontal orientation angle toward the Sun and the optimum time interval of the panel’s movement. The optimum time intervals or panel movement can change the rate of input energy to the panel surface in Iran. For this purpose, a neural network has been trained to estimate the intensity of solar radiation in Iran. After model validation, the intensity of solar radiation has been estimated by selecting adequate geographical regions. Based on the intensity of sunlight, Iran has been divided into ten regions. In these regions, 40 cities have been randomly selected to study the effect of the panel’s angle variations within appropriate time intervals, as well as equal time intervals. The results show that the choice of the mounting system with the possibility of five angles’ implementation can increase the amount of solar energy between 3.9% and 7.4%. Compared to this number of angles at the equal time intervals, the amount of incoming solar energy has increased by 3% to 7%. In the first and second cases, the area of the power plant increases by about 12% to 24% compared to the yearly optimum tilt angle. Moreover, the amount of radiation incoming to the panel with the optimum operating angle is in alignment with the results of PVsyst software.