Optimization of a multi-constraint transport problem using a heuristic approach

A Linear transport problem can be defined as the action of transporting products from "m origins" (or units) to "n destinations" (or customers) at the lowest cost. So the solution to a transportation problem is to organize the transportation in such a way as to minimize its cost. The objective of this paper is to determine the quantity sent from each source (origin) to each destination while minimizing transport costs. Achieving this objective requires a methodology which consists in deploying an algorithm whose purpose is the search for an optimal solution, based on an initial solution. The application is made on a factory producing mechanical parts.

HYDROTHERMAL EXTRACTION OF LITHIUM COMPOUNDS FROM PETALITE Li[AlSi4O10]

Based on studies of the decomposition of pe­ta­lite ore, the hydrothermal method for the extraction of lithium and aluminum compounds from lithium aluminosilicate Li[AlSi4O10] (petalite) has been developed. The studied sample of ore contains, wt. %: Li2O – 0.75 and Al2O3 – 14.65. For unenriched petalite ore with low lithium content, it is proposed to use the hydrochemical method of aluminosilicate processing – Ponomarev – Sazhin method. According to this method, the decomposition of ore is carried out directly in autoclaves by chemical interaction of ore components with NaOH solution in the presence of calcium oxide. The conditions (high temperature and pressure) for the destruction of petalite and the transition of lithium into the liquid phase are created exactly in the hydrothermal process. In this case, lithium and aluminum compounds pass into the solution, and calcium and silicon form a partially soluble compound in the solid phase – sodium-calcium hydrosilicateNa2O·2CaO·2SiO2·2H2O. The degree of extraction of lithium reaches 89–94 %, aluminum reaches 77–95 % within 1 hour at a tempe­rature of 240–280 °C, given caustic modulus 14–18, the concentration of the initial solution of 400–450 g/dm3 of Na2O and the ratio of CaO : SiO2 = 1 : 1 in the reaction mixture. Aluminate or lithium carbonate and other compounds can be obtained from an aluminate solution containing 1.5–2.5 g/dm3 of Li2O and 32–44 g/dm3 of Al2O3. The solid phase formed as a result of decomposition, with a high degree of extraction of lithium from the ore contains a small amount of Li2O in its composition and therefore can be used in the cement industry. Depending on the quality of the decomposed raw material, the course of the hydrothermal process is influenced by a set of factors. With a small content of lithium and aluminum in the ore, the caustic modulus of aluminate solutions (αк = 1,645*Na2O/Al2O3) formed after decomposition is important. Its calculation is required in order to determine the amount of alkaline solution of the required concentration to ensure almost complete decomposition of the ore. This value should be higher the lower the decomposition temperature and the concentration of the initial solution to achieve the same degree of recovery of useful components in the liquid phase. With the same caustic modulus, the efficiency of ore decomposition increases significantly with increasing process temperature and increasing the concentration of the initial solution. This can be seen in the values of the degree of extraction of aluminum, which increases by 12 % with increasing temperature from 240 to 280 °C, while the extraction of lithium remains practically unchanged.

Improved algorithm for minimum zone of roundness error evaluation using alternating exchange approach

Based on the computational geometry technique, an improved algorithm for minimum zone of roundness error evaluation using an alternating exchange method is presented. A minimum zone fitting function was created to enhance the roundness error evaluation. The function uses three candidate points to determine the initial solution: the expected centre, the mean circle radius, and the corresponding zone half-width. The best solution function is designed to use the initial solution as the input to determine the optimum solution for the minimum zone circle. The proposed algorithm was validated using data available in the literature. The roundness error evaluation comparison results demonstrate that the proposed method accurately detects both the centre error magnitude and minimum zone circle and overcomes the insufficiency of using selected colinear points for four selected points.

Optimasi Pendistribusian Air dengan Metode North West Corner dan Metode Modified Distribution di PDAM Wae Manurung Kabupaten Bone

Penelitian ini membahas tentang optimasi pendistribusian menggunakan model transportasi yang menerapkan Metode North West Corner (NWC) dan Metode Modified Distribution (MODI) pada pendistribusian air di PDAM Wae Manurung kabupaten Bone. Data distribusi air diformulasikan dengan model transportasi, sehiggga diperoleh keseimbangan model dengan penambahan variabel dummy dan tabel transportasi distribusi air, diperoleh solusi awal yang fisibel dengan perhitungan menggunakan Metode North West Corner. Berdasarkan solusi awal diperoleh solusi optimum dengan menggunakan Metode Modified Distribution. Hasil penelitian ini menunjukkan bahwa dengan penerapan Model Transportasi terjadi optimasi biaya distribusi air di Kabupaten Bone sebesar 52,22% dibandingkan hasil perhitungan yang dilakukan oleh PDAM Wae Manurung Kabupaten Bone.Kata Kunci: Optimasi, model transportasi, north west corner, modified distribution, distribusi air This study discusses the Optimization using types of transportation model that application North West Corner method (NWC) and Modified Distribution Method (MODI) on the stock of water in PDAM Wae Manurung Bone Regency. The water distribution data is formulated with a transportation model, so that in order to obtain the model is generated a balance model with addition dummy variable and export table water distribution, obtained a feasible initial solution by calculation using North West Corner method (NWC). Based on a feasible initial solution obtained the optimum solution using the Modified Distribution Method (MODI). The results of this study indicate that with the application of the Transportation Model there was a optimization occurs in water distribution costs in Bone Regency in June 2019 of 52.22% compared to the calculation results by PDAM Wae Manurung Bone Regency.Keywords: Optimization transportation model, north west corner, modified distribution, distribution water.

The Effect of Mass Transfer Rate-Time in Bubbles on Removal of Azoxystrobin in Water by Micro-Sized Jet Array Discharge

In this work, the azoxystrobin removal in water by using a micro-size discharge array was investigated, and the removal efficiency can reach as high as 98.1% after 9 min plasma treatment as well as the energy utilization being only 0.73 g/(kW·h). Based on the relationship between the generation of gas bubbles and parameters of gas-liquid discharge, it was found that the variation of applied voltage, gas flow rate and initial solution temperature could cause particle number change, mass transfer rate change and the mass transfer time change, which significantly affected the practical applications at last. The experimental results indicated that when gas flow rate was 0.7 SLM (Standard Liter per Minute) and the initial solution temperature was 297 K with the applied voltage of 8 kV and discharge frequency of 6 kHz, the removal efficiency of azoxystrobin achieved maximum. Based on the analysis results of liquid mass spectrometry, the removal pathways of azoxystrobin were supposed by the decomposed by-products. Toxicity tests indicated that the decomposed products were safe and non-toxic. So, this study may reveal an azoxystrobin degradation mechanism and provide a safe, reliable and effective way for azoxystrobin degradation.

Investigating the Role of the Catalyst within Resorcinol–Formaldehyde Gel Synthesis

Resorcinol–formaldehyde (RF) gels are porous materials synthesized via a sol–gel reaction and subsequently dried, producing structures with high surface areas and low densities—properties that are highly attractive for use in various applications. The RF gel reaction takes place in the presence of a catalyst, either acidic or basic in nature, the concentration of which significantly impacts final gel properties. The full extent of the catalyst’s role, however, has been subject to debate, with the general consensus within the field being that it is simply a pH-adjuster. The work presented here explores this theory, in addition to other theories postulated in the literature, through the synthesis and analysis of RF gels catalysed by mixtures of relevant compounds with varying concentrations. The relationship between catalyst concentration and initial solution pH is decoupled, and the individual roles of both the cation and the anion within the catalyst are investigated. The results presented here point towards the significance of the metal cation within the RF gel reaction, with similar structural properties observed for gels synthesized at constant Na+ concentrations, regardless of the initial solution pH. Furthermore, through the use of alternative cations and anions within catalyst compounds, the potential effects of ions on the stabilization of macromolecules in solution are explored, the results of which suggest a ‘Hofmeister-like’ series could be applicable within the catalysis of RF gel reactions.

PENERAPAN METODE MODIFIED DISTRIBUTION (MODI) UNTUK OPTIMALISASI BIAYA DISTRIBUSI PRODUK ALAT KESEHATAN

The transportation model is the lowest cost plan determination for a distribution process. This research aims to obtain the pattern of distribution of medical device products at PT X so that the costs for the distribution process become more optimal and the needs of product demand to each city can be met. By using Vogel's Approximation Method (VAM) as a viable initial solution and followed by optimization tests to determine the optimal solution with Modified Distribution Method (MODI). The results showed the initial solution of VAM method obtained cost Rp176,645,930 then Modified Distribution Method (MODI) as the optimal solution obtained optimal transportation costs of Rp176,645,210. Based on the results of calculations that have been done shows the results that the distribution of medical devices in PT. X by implementing a transport model can save on distribution costs

IMPLEMENTASI MODEL TRANSPORTASI DISTRIBUSI PRODUK VAKSIN HEPATITIS B MENGGUNAKAN METODE LEAST COST DAN MODIFIED DISTRIBUTION

The transportation method is a method related to optimization model used to minimize the cost of transportation distribution. Distribution of products to various regions requires transportation costs are not small, it requires good planning in order for the availability of goods can be met. The purpose of this study, applying the transportation cost of hepatitis B vaccine distribution from PT. XYZ by using Least Cost Method as the initial solution and Modified Distribution Method (MODI) to optimize so that companies can know the cost of optimal vaccine distribution. The results showed the implementation of transportation model by PT. XYZ with the initial solution using the Least Cost Method obtained the cost of transportation distribution of Rp 45,874,100. then after the optimization of costs by using Modified distribution method the cost of transportation distribution becomes more optimal and the minimization of costs obtained to be Rp 45,767,100.

Preparation of Graphene Oxide Composites and Assessment of Their Adsorption Properties for Lanthanum (III)

In this study, graphene oxide (GO) was prepared using the improved Hummers’ method, and GO was carboxylated and modified into hydroxylated graphene oxide (GOH). Diatomaceous earth (DE), which exhibits stable chemical properties, a large specific surface area, and high porosity, as well as chitosan/magnetic chitosan, was loaded by solution blending. Subsequently, carboxylated graphene oxide/diatomite/chitosan (GOH/DCS) and carboxylated graphene oxide/diatomite/magnetic chitosan (GOH/DMCS) composites were prepared through simple solid–liquid separation. The results showed that the modified GOH/DCS and GOH/DMCS composites could be used to remove lanthanum La(III)), which is a rare earth element. Different factors, such as initial solution concentration, pH of the solution, adsorbent dosage, adsorption contact time, and adsorption reaction temperature, on adsorption, were studied, and the adsorption mechanism was explored. An adsorption–desorption recycling experiment was also used to evaluate the recycling performance of the composite material. The results show that at the initial solution concentration of 50 mg·g−1, pH = 8.0, 3 g·L−1 adsorbent dosage, reaction temperature of 45 °C, and adsorption time of 50 min, the adsorption effect is the best. The adsorption process is more in line with the pseudo-second-order kinetic model and Langmuir model, and the internal diffusion is not the only controlling effect. The adsorption process is an endothermic and spontaneous chemical adsorption process. The maximum adsorption capacity of GOH/DMCS for La(III) at 308K is 302.51 mg/g through model simulation. After four adsorption–desorption cycles, the adsorption capacity of the GOH/DMCS composite for La(III) initially exceeded 74%. So, GOH/DMCS can be used as a reusable and efficient adsorbent.