ARCHAEOLOGICAL HERITAGE OF PREHISTORIC CAVES IN BA THUOC DISTRICT, THANH HOA PROVINCE: PRESERVATION AND PROMOTION

Ba Thuoc is a mountainous district in western Thanh Hoa Province, where more than 20 archaeological sites have been discovered. One of the outstanding features here is the presence of Middle Pleistocene fauna in Lang Trang cave, including fossils of Gigantopithecus blacki, a giant ape. The appearance of early modern human fossils in the Late Pleistocene proves that Vietnam was the site of the earliest modern human evolution in Southeast Asia. In Ba Thuoc district, human communities were in continuous residence from 30,000 to 7,000 years BP and developed the Dieu stone craft industry. This industry merged with the Hoabinhian industry in the development process, creating a cultural nuance for the land of Ba Thuoc. By 7,000 years BP, the boundary between the two industries was virtually nonexistent. The prehistoric inhabitants here contributed to the formation of Middle Neolithic cultures in North Central Vietnam. In addition, the caves in Ba Thuoc were also places for the mountain-dwelling inhabitants of the Dong Son culture to visit and bury their dead in the centuries before and after the beginning of the common era. In this study, we systematized the documents on monuments and artifacts, and evaluated the outstanding cultural heritage of the prehistoric caves in Ba Thuoc district, which need to be preserved and promoted in the present day

Design of diesel engine's optimal control maps for high efficiency and emission reduction

The objective of this thesis is to create static optimal control maps of diesel engines for high efficiency and emission reduction. The calibration tool to be used to create the control maps, named "Off-line parameterization tool", was designed based on the Design of Experiments method. The optimization goal is to minimize the Brake Specific Fuel Consumption (BSFC) of the engine by the engine's input parameters and under some emission constraints. The tool was designed to be able to work both fully automatically and semi-automatically. Though most of the previous researches on engine calibration have used the Design of Experiments approach, their implementations in choosing experimental design types and optimization process are different compared to this thesis. The unique aspect of this research lies on the significant properties of the Off-line parameterization tool. Firstly, this tool is flexible, it is able to work with multiple inputs and multiple outputs. Secondly, it can reduce the calibration time as the engine running time is kept as small as possible and all the data processing work is done automatically

HOABINHIAN IN VIETNAM AND ECONOMIC ACTIVITIES FROM 20,000 TO 7,000 YEARS BP

This article studies the basic economic activities of Hoa Binh cultural inhabitants in the period of 20,000 to 7,000 years BP, including tool making, hunting, gathering, and primitive agriculture. The research results have identified a number of key economic characteristics of Hoa Binh cultural residents and evaluated the effectiveness of human methods of finding and gathering food under the fluctuations of the natural environment during the late Pleistocene to early Holocene in northern Vietnam. Little evidence directly related to cultivation and animal husbandry has been found at Hoa Binh cultural sites, so the issue of Hoa Binh agriculture is still a working hypothesis that needs to be studied further

Enhancing the ride comfort of the off-road vibratory roller cab by adding damper hydraulic mount

In order to improve the vibratory roller’s ride comfort, a 3-D nonlinear dynamic model of the vehicle interacting with the off-road terrain is established. A damper hydraulic mount is studied and combined with the cab’s rubber mounts to simulate and evaluate the performance of the ride comfort. The weighted RMS acceleration responses of the vertical driver’s seat, the cab’s pitch and roll angle are chosen as objective functions. The results show that the cab’s rubber mounts combined with the damper hydraulic mount are clearly improved the ride comfort under various operating conditions. Especially, with damping coefficients cc3,4= 1.8 kN.s.m-1, the weighted RMS values of the vertical driver’s seat, the cab’s pitch and roll angle are greatly reduced by 27.8 %, 22.7 % and 64.3 % in condition of the vehicle traveling, and by 23.8 %, 20.0 % and 63.7 % in condition of the vehicle compacting on an elastic-plastic terrain

Evaluating the effect of the working conditions on the ride comfort and road friendliness of the heavy truck

This study proposes a nonlinear dynamic model of the heavy trucks to evaluate the influence of the various working conditions on the ride comfort and road friendliness of the heavy vehicles based on Matlab/Simulink software. The weighted root mean square (RMS) acceleration responses of the vertical driver’s seat, the cab’s pitch and roll angles, and the dynamic load coefficient (DLC) are chosen as objective functions. The influence of the vehicle velocity and loads on the different road surfaces are evaluated based on the standard ISO 2631-1. The results show that the vehicle’s ride comfort is clearly affected on the road surfaces of ISO level C and D at the range of the vehicle velocity. Especially, the vehicle’s ride comfort is very poor at the velocity of 10-30 m.s-1 on ISO level D. The road friendliness of the vehicle is greatly decreased in the condition of the half-loaded vehicle. Particularly the vertical dynamic wheel loads at 2nd axle strongly affect the road damage at the velocity of 10-30 m.s-1