Economic performance of Vietnam, 1976-2000: New evidence from input-output model

This study provides a concise introduction to the economic history of Vietnam from 1976 to present. We identify different phases of the development of the Vietnamese economy, from its unification after a Vietnam war to the current phases of the transition (1989-2000) and propose a specific pattern of transition in the case of Vietnam. This research is the first attempt to make a synthesis quantitative analysis of socio-economic aggregate data during different phases of the Vietnamese economy in 1986-2000, in which different national input-output tables (1989, 1996 and 2000) in constant prices have been employed. The economic performances are investigated from three aspects: (i) evolution of domestic final demand; (ii) evolution of international trade structure and (iii) the technological change. The analysis shows economic history of Vietnam from 1986 up to present as a continuous evolutionary process and integration in to the international market is inevitable. Government programmes only played a vital role of accommodator to the economic changes of the Vietnamese economy.Input-output analysis, Vietnamese economy, Economic history, Transition economy, Macro-economic policy

A hybrid heuristic optimization algorithm PSOGSA coupled with a hybrid objective function using ECOMAC and frequency in damage detection

Presence of damage leads to variation in modal properties of observed structures. The majority of studies use the changes in natural frequencies for damage detection. The reason is that the frequencies are often easily measurable with high accuracy by using reasonable sensors. However, frequencies are more sensitive to environmental effects, such as temperature, in comparison with mode shapes. Besides, defects in symmetric structures can cause the same changes in frequency. In contrast, mode shapes are more sensitive to local damage because they own local information and are independent of symmetric characteristics. These make mode shapes have dominant advantages in detecting nonlinear and multiple damage. ECOMAC is an index derived from mode shapes. It is a fact that these indices are not always possible to detect faults successfully in structures. Therefore, in this paper, a hybrid optimization algorithm, particle swarm optimization – gravitational search algorithm, namely PSOGSA, is used to improve the accuracy of infect detection using a hybrid objective function combined ECOMAC and frequency based on the inverse problem. Numerical studies of a two-span continuous beam, a simply supported truss, and a free-free beam, are utilized to verify the effectiveness and reliability of the proposal. From the obtained results, the proposed approach shows high potential in damage identification for different structures

A hybrid heuristic optimization algorithm PSOGSA coupled with a hybrid objective function using ECOMAC and frequency in damage detection

Presence of damage leads to variation in modal properties of observed structures. The majority of studies use the changes in natural frequencies for damage detection. The reason is that the frequencies are often easily measurable with high accuracy by using reasonable sensors. However, frequencies are more sensitive to environmental effects, such as temperature, in comparison with mode shapes. Besides, defects in symmetric structures can cause the same changes in frequency. In contrast, mode shapes are more sensitive to local damage because they own local information and are independent of symmetric characteristics. These make mode shapes have dominant advantages in detecting nonlinear and multiple damage. ECOMAC is an index derived from mode shapes. It is a fact that these indices are not always possible to detect faults successfully in structures. Therefore, in this paper, a hybrid optimization algorithm, particle swarm optimization – gravitational search algorithm, namely PSOGSA, is used to improve the accuracy of infect detection using a hybrid objective function combined ECOMAC and frequency based on the inverse problem. Numerical studies of a two-span continuous beam, a simply supported truss, and a free-free beam, are utilized to verify the effectiveness and reliability of the proposal. From the obtained results, the proposed approach shows high potential in damage identification for different structures

A DOUBLE-SHRINK AUTOENCODER FOR NETWORK ANOMALY DETECTION

The rapid development of the Internet and the wide spread of its applications has affected many aspects of our life. However, this development also makes the cyberspace more vulnerable to various attacks. Thus, detecting and preventing these attacks are crucial for the next development of the Internet and its services. Recently, machine learning methods have been widely adopted in detecting network attacks. Among many machine learning methods, AutoEncoders (AEs) are known as the state-of-the-art techniques for network anomaly detection. Although, AEs have been successfully applied to detect many types of attacks, it is often unable to detect some difficult attacks that attempt to mimic the normal network traffic. In order to handle this issue, we propose a new model based on AutoEncoder called Double-Shrink AutoEncoder (DSAE). DSAE put more shrinkage on the normal data in the middle hidden layer. This helps to pull out some anomalies that are very similar to normal data. DSAE are evaluated on six well-known network attacks datasets. The experimental results show that our model performs competitively to the state-of-the-art model, and often out-performs this model on the attacks group that is difficult for the previous methods

Two algorithms for detection of mutually occluding traffic signs

The robust identification of the traffic signs represents the first and one of the most important steps in the development of a traffic sign recognition (TSR) system. Traffic signs detection usually involves a color segmentation process that uses the information related to the chromatic properties of the road signs. Since the traffic video data is captured in diverse road and weather conditions, the problem relating to traffic sign detection is quite challenging. Among several issues that need to be addressed during this processing stage, the problem generated by mutually occluding traffic signs (mutual occlusion occurs when one traffic sign partially occludes the surface of other road signs) that are attached to the same pole require special attention. In these situations the color segmentation process fails to correctly identify the regions that are associated with the traffic signs. These traffic sign detection failures compromise the performance of other stages of the TSR system and in this paper we propose two approaches that address the segmentation of mutually occluding traffic signs. The first approach uses the information associated with the inner parts of the traffic signs, while the second approach applies the watershed transform to identify the signs that have their borders in contact or are mutually occluding

CAUSE-EFFECT RELATIONS AND OPTIMIZATION OF TABLET CONTAINING EUCOMMIA ULMOIDES AND GARDENIA JASMINOIDES SPRAY-DRIED EXTRACTS

Objective: The E. ulmoides and G. jasminoides (EG) tablets containing 67 mg E. ulmoides spray-dried extract (ESE) and 173 mg G. jasminoides spray-dried extract (GSE) were prepared by employing the direct compression method. Due to the poor flowability and compressibility of the two spray-dried extracts, various excipients were added at different ratios so that the blends can be compressed into tablets with the required standards. This study aimed at the cause-effect relations and optimization of the EG tablet formulation.Methods: Different diluents including dibasic calcium phosphate anhydrous (DCPA), silicified microcrystalline cellulose (SMCC), spray-dried lactose (SDL) and the active ingredients (blend of ESE and GSE at the ratio of 67:173, w/w) were separately investigated their own physical properties. The binary mixtures of the active ingredients with different ratios of DCPA, SMCC, and SDL were evaluated their flowability. D-optimal design based on three independent variables (% DCPA, % croscarmellose sodium (CCS) and % SMCC) was applied to evaluate the cause-effect relations and optimize the EG tablet formulation. The weight variation, disintegration time, hardness and friability were investigated as four dependent variables.Results: The flowability of the powders was found to be affected by the particle size distribution, particle shape and density. The three diluents could significantly improve the flowability of the active ingredients. All independent variables had significant effects on the dependent variables. An increase in % SMCC reduced the weight variation, hardness and increased the friability of tablets. Disintegration time was found to be in the negative relations with % CCS. The tablet hardness was in positive relations with % DCPA. The optimized EG tablet formulation composed of 9 % DCPA (w/w), 35 % SMCC (w/w), and 14 % CCS (w/w) of the excipient blend. The weight variation, disintegration time, hardness and friability of the optimized EG tablets were found to be 1.8 %, 11.7 min, 61.4 N, and 0.5 %, respectively.Conclusion: The ESE and GSE could be formulated into tablet by using direct compression method. The cause-effect relations and optimization of EG tablet formulation were studied and reported for the first time

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

Energy Lost in a Hydrogel Osmotic Engine Due to a Pressure Drop

Utilizing hydrogels to harvest salinity gradient energy from solutions of different salinities has recently attracted interest. Polyelectrolyte hydrogels exhibit cyclic swelling/deswelling when alternately exposed to freshwater and seawater. This can be utilized to convert the mixing energy of the two solutions into mechanical energy. Hydrogels consisting of a semi-interpenetrating network (semi-IPN) of poly(4-styrene sulfonic acid-co-maleic acid) sodium salt and polyacrylic acid was prepared at various cross-linking densities. The energy lost due to a pressure drop in the system during the deswelling/swelling process of these hydrogels is examined, and the effects of tubing dimensions, hydrogel cylinder size, gel particle size, and the volume fraction within the hydrogel cylinder occupied by the flowing liquid (ε) are investigated. In addition, a small-scale osmotic engine was compared to a scaled-up system. ε was found to be the factor that had the largest effect on the energy loss. It was found that ε is strongly dependent on the degree of swelling of the hydrogels. When the hydrogels swell, they deform more easily under pressure. This markedly decreases ε, thereby inducing a high pressure drop in the system and a correspondingly large energy loss. Accordingly, the pressure drop when pumping through the hydrogel is the major contributor to the energy loss in the system. When the hydrogel particles deform too much, the energy needed to pump the flowing liquid through the hydrogels exceeds the energy produced by the system. Developing a hydrogel system that deforms less in its swollen state is therefore essential for improving the energy efficiencies of these osmotic engines.publishedVersio

Force reflecting joystick control for applications to bilateral teleoperation in construction machinery

This paper presents a simple and effective force reflecting joystick controller for applications to bilateral teleoperation in construction machinery. First, this controller is a combination of an advanced force reflecting gain tuner and two local adaptive controllers, master and slave. Second, the force reflecting gain tuner is effectively designed using recursive least square method and fuzzy logics to estimate directly and accurately the environmental characteristics and, consequently, to produce properly a force reflection. Third, the local adaptive controllers are simply designed using fuzzy technique and optimized using a smart leaning mechanism to ensure that the slave follows well any given trajectory while the operator is able to achieve truly physical perception of interactions at the remote site. An experimental master-slave manipulator is setup and real-time control tests are carried out under various environmental conditions to evaluate the effectiveness of the proposed controller

The influence of economic factors on the sustainable energy consumption: evidence from China

Recently, sustainable energy consumption has been a significant factor in reducing environmental degradation due to the high economic growth, and this phenomenon demands more attention of scholars and policymakers. Thus, the current literature examines the impact of economic factors such as economic growth, foreign direct investment (FDI), inflation, and population growth on sustainable energy consumption (SEC), particularly in renewable energy consumption (REC) in China. This study used secondary data collection methods extracted from world development indicators (WDI), incorporating stationary tests like Phillips-Perron (PP) and Augmented Dickey-Fuller (ADF) to check the unit root of the constructs. The time-series data involved are from 1981 to 2019. The autoregressive distributed lag (ARDL) model was utilized to examine the association among the variables. The results indicated that economic growth, FDI, inflation, and population growth were positively associated with SEC in China. This study provides the guidelines to the policymakers to develop policies related to the SEC