Tạp chí Khoa học và Công Nghệ

LPSO an efficient algorithm scheduling of scientific workflows in cloud computing

Phan Thanh Toàn — 2017-10-12

No available abtract

Combining fuzzy probability and fuzzy clustering for multispectral satellite imagery classificationr

Mai Đình Sinh — 2017-10-12

No available abtract

Effect of hot drying on the essential oil content and colour characteristics of peppermint

Nguyễn Thị Yến Chi — 2017-10-13

The main objectives of this study were to investigate the effect of different temperature of hot air drying on the qualities of dried peppermint, including essential oil content, colour parameters, and visual sensory quality and to develop mathematical models for the colour change kinetics. The drying experiments were carried out at five air temperatures, 40, 50, 60 70 and 80 ‘’c. The colour parameters for colour change of the materials were quantified by the Hunteri (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) system. These values were also used for calculation of total change (AE) as well as chroma, hue angle and Browning index, A consumer preference test was conducted with 80 consumers to as^ss the colour quality of 05 dried peppermint samples. The results showed that the decrease in essential oils content at high drying temperature is higher than at low temperature. Least Squares regression was used to determine the relationship between the visual sensory scores of consumer taster and the Hunter Lab values It was observed that L, a, AE and hue angle values were fitted to the zero-order model, while b and chroma were fitted to the first-order model

Isolation and screening of antimicrobial compounds of micromonospora strains isolated from Halong-Cat Ba bay's sediments

Lê Thị Hồng Minh — 2017-10-13

No avaialbe abstract

An estimation of bamboo borer biomass in Son La province, Northwestern Vietnam and remarks on its parasitic characteristic

Phạm Quỳnh Mai — 2017-10-13

The population of Vietnam has been rapidly increased and would reach 100 million people in the near future It is very likely that the soiưces of traditional food are insufficient to the whole popul^ion. Therefore, a study for sustainable usage of insects as a supplemental food for human in the ftifure is dearly required. In fact. larvae of bamboo borer, Omphisa fuscidentalis has been used as a kind of foods by local people m mountainous provinces in northern Vietnam It also appears as a trade product in local markets. This paper presents the results of recent studies on the infested rales of bamboo borer larvae from different bamboo species. An assessment of Its parasitic characteristics and an estimation of biomass in Son La province are also given in this paper.

Synthesis of hydroxyl terminated liquid natural rubber by oxidative deproteinized natural rubber

Lê Đức Giang — 2017-10-13

Hydroxyl terminated liquid natural rubber (HTLNR) was prepared by the depolymerizatioQ of deproteinized natural rubber (DPNR) in mixture of toluene and water at 60 °c for 24 hours in the presence of ammonium persulfate as an initiator and tehahydrofuran (THF) as a homogenizing agent. GPC analysis revealed that the number-average molecular weight (M„) and weight-average molecular wei^t (M„.) of HTLNR were found to be 4.334x10° g/moi and 11.702x10^ g/mol. respectively, with polydispersity index (PDI) of 2.7. The chemical structure of HTLNR was determined by FTIR and 'H-NMR and '^C-NMR spectroscopic analysis. Based on the analytical data the mechanism of depolymerization and hydroxylation of NR to form HTNR was also suggested.

Oxidized maize starch: characterization and its effect on the biodegradable films

Đào Phi Hùng — 2017-10-13

No avaiable abstract

Effect of molecular structure of pophyrins on their semiconducting properties

Hoàng Mai Hà — 2017-10-13

In this word, we report on tlie fabrication of organic field-effect transistors (OFRTs) using solution processable semiconducting porphyrins 4TBPZ and 2TBPZ. The eflect of semiconductor crystal structure on the performance of OFE I s was investigated These singlecrystal devices were revealed to exhibit good performance with a maximum carrier mobility for hole of 0.40 cm- V' s ' and high current on/off ratios. The present work, representing our continuous efforts in understanding the relationship between molecular structure costal packing, and OFET perfomiance of semiconducting porphyrins, will be expected to conmbutc to the design of new porphyrin derivatives for electronic/optoelectronic applications

Effect of laser power on the molten pool temprature and layer thickness at the curvature radius of thin-wall part fabricated by laser direct metal forming

Đoàn Tất Khoa — 2017-10-13

To discuss the effect of laser power on the molten pool temperature and layer thickness at the curvature radius of thin-wali parts, the numerical simulation and expemncntal was studied The numerical results showed that the molten pool temperature of the thin-wall increases with the layer number, and the molten pool temperature of thin-wall cylinders were increa.sed when curv'aturc radius decreased The rules of laser power changing with the layer number and ciinuture in ilie processing of the thin-wall blade can be obtained when keeping molten pool temperature stable. According to the numerical results, the thin-wall blades were fabneated by experiments. The experimental results showed that the excessive build-up occ^uired and unevenness thickness layer at small radius ccimcr with constant laser power because of the increase of energy density at comers, while varied laser power is more Uniterm than the constant laser power, which IS in agreemeni with the numerical simulation.

Effect of some dispersing auxiliaries on nanosilica dispersion into passive chrom trivalent solution

Trương Thị Nam — 2017-10-13

No avaiable abstract

Application of fuzzy logic for controlling mechanism of ralative manipulation robot (MRM robot)

Phan Bùi Khôi — 2017-10-13

In robot control, mathematical equations describing dynamic behaviors of robots are usually complicated. Additionally, the components such as inertial and friction parameten appearing in these equations are very difficult to determine exactly. With robots having complex structure .such as parallel robots. MRM robots etc., the derivation of dynamic equations becomes more difficult and sometimes cannot obtain analytically. In those cases, controlling robot based on its equations of motion IS quite hard. Applying fuzzy logic for robot control can overcome the mentioned drawbacks. This IS because fuzzy control algorithm gives favorable condition to deal with the lack of adequation as well as inaccuracy of components in robot’s dynamic equations. Furthermore, the fuzzy rules are created by clauses which based on human logic so It IS easily to understand and implement This paper discusses the application of fuzzy logic for controllini MRM robots. To compare the results obtained from fuzzy control, this paper are also adressed the use of the computed torque algorithm to control MRM robots.

Bending and free vibration analysis of functionally graded plates using new eight unknown shear deformation theory by finite element method

Nguyễn Văn Long — 2017-10-13

No avaiable abstract

On the critial velocity of a vehicle moving on the bridge

Nguyễn Văn Khang — 2017-10-13

Vibration model of a vehicle on the bridge IS modeled by a mass - spring - damper system moving on an elastic beam J his paper presents the results of a new study on determ.nine tile critical velocity of a vehicle moving on the beam bridge. The cniicai velocity'of the vehicle calculated according to the new model is much smaller than that calculated according to the old

Application of data assimilation for parameter correction in super cavity modelling

Trần Thu Hà — 2017-10-13

On the imperfect water entry, a high speed slender body moving in the forward direction rotates inside the cavity. The super cavity model describes the very fast motion of body in water. In the super cavity model the drag coefficient plays important role in body’s motion. In some references this drag coefficient is simply chosen by different values in the interval 0.8-1.0. In some other references this drag coefficient is wntten by the formula /t =Cpo{l + cr)cos^ Of with Ơ is the cavity number, oc IS the angle of body axis and flow direction, CoQ is a parameter chosen from the interval 0.6-0 85. In this paper the drag coefficient k = (1 + ơ)cos’ Of is

written with fixed Coo = 0.82 3nd the parameter ft, is corrected so that the simulation body velocities are closer to observation data. To find the convenient drag coefficient the data assimilation method by differential variation is applied. In this method the observing data is used in the cost function The data assimilation is one of the effected methods to solve the optimal problems by solving the adjoin problems and then finding the gradient of cost function.