Optimizing EDM for titanium alloys: an in-depth comparison of five MCDM techniques

This experimental study investigates the effect of the cutting parameters of the Electrical Discharge Machining (EDM) process of Ti-6Al-4V alloy material on surface roughness (Ra), cutting time (t) and Material Removal Rate (MRR) then solve the Multiple Objective Optimization Problem using separate Multi-Criteria Decision-Making (MCDM) methods namely Entropy-Weighted TOPSIS (E-TOPSIS), MOORA, SAW, VIKOR, and WPM. Focusing on nine 3-levels variants including Operating Voltage (OV), Pulse-On Time (Ton), Pulse-Off Time (Toff), Short-Circuit Off Time (AFF), Secondary Voltage (SV), Feed Rate (WF), Tension (WT), Water Pressure (WL) and Material Cutting Speed (F). Due to the large number of variants studied, the Taguchi L27 experimental design was chosen to reduce the number of experiments while still ensuring reliability in assessing the impact of technological parameters on responses in the study. The optimization results from the different methods indicated two distinct optimal outcomes. According to the E-TOPSIS, MOORA, and SAW, the optimal result is a Ra of 3.27 µm, a t of 7.37 min, and an MRR of 7.45 mm3/min. This result suggests a balanced and harmonious optimization among all criteria. On the other hand, the figures VIKOR and WPM methods are 2.87 µm, 9.57 min, and 5.74 mm3/min, respectively. These results indicate a higher priority for certain criteria, reflected in the lower Ra, longer cutting time, and a smaller MRR in comparison to the figures for the remaining MCDM methods. The different optimal results achieved by various methods highlight that each method is suited to and excels with different sets of values. Therefore, in each specific research or production process, comparing and choosing results calculated by different methods provides a comprehensive view, aiding in making appropriate decision

The Potential of the Rice Value Chain in the Mekong Delta to Develop High Value Export Markets

This study aims at analyzing the current status of the rice value chain in the Mekong Delta focusing on export channels. The study assessed primary data collected from respondents related to the chain in the year 2020. Research results show that about 35% of rice in the region is used for export, of which most of the rice exported belongs to the high quality segment. Although improvements achieved recently, the regional rice value chain still faces many limitations. The study proposes solutions to strengthen the rice value chain and increase the volume of high quality rice exported into more demanding high income markets

Experimental results of gaslift process

In the paper, the investigation results of periodical gas-lift flows in vertical pipes using experiment method are presented. The experiment facilities consist of flow measurement equipment, gas and fluid supplier facilities, tubing system. To study the influence of medium physical and dynamical characteristics on the process efficiency, two liquid-gas systems are used, namely, water-air and spindle oil-air. The objects of investigation are to obtain data from tests conducted in some conduits and to analyse the influence of system physical, geometrical and etc. parameters such as: initial liquid height in the conduits, gas injected volume, conduit diameter, conduit configuration and etc. on the considered process

ViHOS: Hate Speech Spans Detection for Vietnamese

The rise in hateful and offensive language directed at other users is one of the adverse side effects of the increased use of social networking platforms. This could make it difficult for human moderators to review tagged comments filtered by classification systems. To help address this issue, we present the ViHOS (Vietnamese Hate and Offensive Spans) dataset, the first human-annotated corpus containing 26k spans on 11k comments. We also provide definitions of hateful and offensive spans in Vietnamese comments as well as detailed annotation guidelines. Besides, we conduct experiments with various state-of-the-art models. Specifically, XLM-R$_{Large}$ achieved the best F1-scores in Single span detection and All spans detection, while PhoBERT$_{Large}$ obtained the highest in Multiple spans detection. Finally, our error analysis demonstrates the difficulties in detecting specific types of spans in our data for future research. Disclaimer: This paper contains real comments that could be considered profane, offensive, or abusive.Comment: EACL 202

An algorithm for simultaneous determination of pressure and temperature distribution in oil-producing tube flow and the counter flow in gas-lift annulus

An algorithm for simultaneous determination of pressure and temperature distribution in oil-producing tube flow and the counter flow in gas-lift annulus has been proposed. The algorithm is based on a double loop iterative procedure and shooting method. The two-phase flow calculation for pressure Used in the algorithm is based on improved methods of Beggs and Brills, Orkissewski or Hagedorn and Brown. The numerical implementation for an example is presented to assure the applicability of proposed algorithm

The impact of productivity on export transitions: revisited evidence from the Vietnamese manufacturing sectors

The effect of total factor productivity (TFP) on exports particularly interests policy-makers and economists, but empirical evidence is ambiguous. This paper uses the 6-wave panel data in 2010-2015 to investigate the impact of TFP on export transitions at the firm level. We distinguish different types of export transitions, namely start, stop, continuity, fluctuation, and striving, and different phases of export transition. The Generalised Method of Moments (GMM) estimation is applied to control for endogeneity and unobserved time-invariant specific components. The results reveal that (i) the effect of productivity on export (the self-selection hypothesis) is heterogeneous, depending on specific sectors and types and phases of export transitions; (ii) productivity growth does not necessarily result in positive effects on and lead to participation in types and phases of export transitions. Our results also reveal strong evidence of favourable sunk cost in long-run export striving in nearly all sectors, and unlike previous studies, empirical results show a negative effect of sunk cost in some manufacturing sectors. Policy-makers should create dynamic comparative advantages and favourable environments for new exporters, focus the relevant policies on productivity stimulus, and strengthen the likelihood of survival for the domestic firms in the competitive global markets

Computation of limit and shakedown using the NS-FEM and second-order cone programming

This paper presents a novel numerical procedure for computation of limit and shakedown using node-based smoothed finite element method (NS-FEM) in combination with second-order cone programming (SOCP). The obtained discretization formulation is then cast in a form which involves second-order cone constraints, ensuring that the underlying optimization problem can be solved by highly efficient primal-dual interior point algorithm. Furthermore, in the NS-FEM, the system stiffness matrix is computed using the smoothed strains over the smoothing domains associated with nodes. This ensures that the size of the resulting optimization problem is kept to a minimum. The efficiency of the present approach is illustrated by examining several numerical examples