Achieving the successful lean implementation at manufacturing companies in Vietnam: Awareness of critical barriers

This study focuses on identifying the critical barriers/difficulties and exploring the roots of barriers/difficulties for successful Lean implementation at manufacturing companies in Vietnam. The literature review and in-depth interviews are applied in this study. The literature review is done to review and to obtain experiences of the inhibitors of Lean Implementation from previous studies. An in-depth interview is conducted with eight experts of eight manufacturing companies deployed Lean to explore and identify the critical barriers/difficulties for Lean implementation successfully. As a result, it finds that seven key barriers inhibiting the successful Lean implementation come from the leadership; the employees; the workplace; resources; operation process; the integration with customers; and from the integration with suppliers. These challenges are not easy and take a lot of time to overcome, though, this study provides helpful advice for business in Vietnam who has plans to follow Lean implementation in looking back to the company and restructuring strategies, objectives so that Lean implementation process would be more efficient and more open

Economic impact of climate change on agriculture: a case of Vietnam

Food security, agricultural exports, and livelihoods have improved by rapid agricultural expansion in the previous 30 years. In the coming decades, warming trends and human pressures are expected to exacerbate the impact of climate change on agriculture. A time series of data from 1990 to 2020 examines the economic effects of climate change on Vietnamese farm production. After using the Augmented Dickey-Fuller and Philips-Perron unit root tests, the ARDL bounds testing technique estimates short and long-run cointegration. They found long-run cointegration between the variables. A positive influence of CO2 emissions is identified, although negative impacts of average temperature and rainfall are found. But only in the short term can energy consumption benefit agriculture. Non-climatic factors like crop production and fertiliser consumption have beneficial short- and long-term impacts on agriculture production and yield. Juselius Jhansen As well as proving long-term cointegration between variables. The report advises the Vietnamese government to create and implement many adaptation programmes to preserve the agriculture industry from climate change.Nguyen Van Huong (Faculty of Economics, Hung Yen University of Technology and Education (UTEHY)), Bui Thi Minh Nguyet (Vietnam National University of Forestry), Hoang Van Hung (Faculty of Economics, Hung Yen University of Technology and Education (UTEHY)), Hoang Minh Duc (Faculty of Economics, Hung Yen University of Technology and Education (UTEHY)), Nguyen Van Chuong (University of Financial and Business Administration (UFBA)), Do Minh Tri (Nguyen Van Linh Political School), Phung Van Hien (National Academy of Public Administration (NAPA))Includes bibliographical references

Using lake sediments to assess the long-term impacts of anthropogenic activity in tropical river deltas

Tropical river deltas, and the social-ecological systems they sustain, are changing rapidly due to anthropogenic activity and climatic change. Baseline data to inform sustainable management options for resilient deltas is urgently needed and palaeolimnology (reconstructing past conditions from lake or wetland deposits) can provide crucial long-term perspectives needed to identify drivers and rates of change. We review how palaeolimnology can be a valuable tool for resource managers using three current issues facing tropical delta regions: hydrology and sediment supply, salinisation and nutrient pollution. The unique ability of palaeolimnological methods to untangle multiple stressors is also discussed. We demonstrate how palaeolimnology has been used to understand each of these issues, in other aquatic environments, to be incorporated into policy. Palaeolimnology is a key tool to understanding how anthropogenic influences interact with other environmental stressors, providing policymakers and resource managers with a ‘big picture’ view and possible holistic solutions that can be implemented

Synthesized BiVO4 was by the co-precipitation method for Rhodamine B degradation under visible light

Recently, BiVO4 photocatalysts has been received much attention in field of catalysts. Because it can be used to degrade harmful organic catalysts in visible light, irradiation produces CO2, H2O and less harmful organic matter. In this study, we have successfully synthesized a BiVO4 photocatalysts via co-precipitation method in the presence of urea and different calcined temperatures. The survey calcined temperatures as 300°C; 350°C; 400°C and 450°C. The obtained materials were characterized by Scanning electron microscope (SEM) and X-ray diffraction (XRD). The photocatalytic activity was evaluated by the photocatalytic degradation of rhodamine B (RhB) degradation under visible compact Philip lamp (40W) light irradiation. The result indicates that all samples calcined are monoclinic scheelite structure of BiVO4. The BiVO4-350°C sample performed the best in the photodegradation of RhB

A facile synthesis and properties of bismuth vanadate (BiVO4) photocatalyst by hydrothermal method

In this study, BiVO4 photocatalysts were synthesized by hydrothermal method using Bi(NO3)3 5H2O and NH4VO3 as raw materials followed by calcination at different temperatures in the range from 350 °C to 600 °C. The as-synthesized BiVO4 samples were characterized by a number of physicochemical techniques including X-ray diffraction (XRD), Raman analysis, Scanning Electron Microscopy (SEM), and UV-Visible (UV-Vis) light diffuse reflectance spectrophotometry. The effect of temperatures calcination on structure, surface morphology, visible-light photocatalytic activity and light absorption performance of BiVO4 was discussed in details

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Enhanced Boost Factor for Three-Level Quasi-Switched Boost T-Type Inverter

A new modulation strategy has been introduced in this paper in order to enhance the boost factor for the three-level quasi-switched boost T-type inverter (3L-qSBT2I). Under this approach, the component rating of power devices is significantly decreased. Moreover, the use of a larger boost factor produces a smaller shoot-through current. This benefit leads to reducing the conduction loss significantly. Furthermore, the neutral voltage unbalance is also considered. The duty cycle of two active switches of a quasi-switched boost (qSB) network is redetermined based on actual capacitor voltages to recovery balance condition. Noted that the boost factor will not be affected by the proposed capacitor voltage balance strategy. The proposed method is taken into account to be compared with other previous studies. The operation principle and overall control strategy for this configuration are also detailed. The simulation and experiment are implemented with the help of PSIM software and laboratory prototype to demonstrate the accuracy of this strategy

An DPWM for Active DC-Link Type Quasi-Z-Source Inverter to Reduce Component Voltage Rating

The conventional DC-link type quasi-Z-source inverter has been known as a buck&ndash;boost inverter with a low component voltage rating. This paper proposes an active DC-link type quasi-Z-source inverter by adding one active switch and one diode to the impedance-source network to enhance the voltage gain of the inverter. As a result, the component voltage rating of the inverter is significantly reduced, which is demonstrated through some comparisons between the proposed topology and others. A discontinuous pulse width modulation (DPWM) scheme is proposed to control the inverter, which reduces the number of commutations compared to the traditional strategy. Under this approach, the insertion of a shoot-through state does not cause any extra commutations compared to the conventional voltage-source inverter. Details about control implementation, steady-state analysis, and design guidelines are also presented in this paper. Simulation and a laboratory prototype have been built to test the proposed inverter. Both buck and boost operations of the proposed inverter are implemented to validate the performance of the inverter

A PWM Scheme for Five-Level H-Bridge T-Type Inverter with Switching Loss Reduction

In this paper, a new pulse width modulation (PWM) scheme using an offset function to reduce switching loss in the five-level H-bridge T-type inverter (5L-HBT2I) is proposed. The proposed modulation technique is implemented with a third harmonic offset voltage function. A new control voltage, that is adding the offset voltage into the initial control, is shifted to the top or bottom position of the carrier, simultaneously&mdash;where the absolute value of its load current is high or medium in comparison to other phase load currents. Due to reducing the intersection between a control voltage and the carriers, the number of switch commutations of the inverter is reduced. As a result of reducing the number of commutation count with a high current at the non-switching position, the switching losses of the inverter are decreased. Analysis and comparison of switching losses on the two-level and three-level inverters, which are components of 5L-HBT2I are presented. The power loss analysis on the 5L-HBT2I is performed. The proposed technique implements the switching loss reduction strategy based on setting the operation of the two-level inverter in six-step mode. PSIM software is used to clarify the proposed technique. The simulation results show that the total switching losses of the proposed technique in 5L-HBT2I reduce in comparison to the conventional sine PWM technique. A prototype is built to validate the proposed scheme. Simulation and experimental results match the analysis