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Online since: January 2016
Authors: Pavol Pauliny
Firstly, there are the conditions themselves – physical properties of the material and construction, conditioned by the use of a specific type of stone, the method of placing and the solution of construction details.
In some cases, several of the aforementioned factors combined contribute to the deterioration of stone structures[1].
The change of function is also connected to different requirements for the thermo-physical properties of interior spaces.
In case of perimeter structures, this is mostly the matter of energy criteria relating to heating, air exchange, achievement of minimum thermal insulation properties[2] and achievement of the minimum temperature of interior surface.
The building aspects analysis revealed that the existing state of salinization has been caused by several factors.
Online since: May 2016
Authors: A.B. Abdullah, Z. Samad, N.A. Ghaffar
Samad School of Mechanical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia.
But the main problem of drilling is excessive tool wear that may affect the quality of the holes.
Its combine two or more materials to exhibits various properties.
Drilling-induced damage, such as spalling, delamination, edge chipping, fiber pullout, crack formation, and excessive tool wear, may affect structural integrity [6-8].
Figure 3: The deviation of the hole diameter Other factor that can be discussed is on the defects that occur at the hole.
Online since: September 2023
Authors: Carpoforo Vallellano, Fernando Mas, Guzman Domínguez-Domínguez
Problem Formulation The main concern about scratches in metallic components in aerospace industry is their effect on mechanical properties.
In the first case, it is not expected to have a significant influence on the mechanical properties of the part.
The clad layer has different mechanical properties and different corrosion resistance, so the behavior of the scratch in the clad layer is expected to be than in the base material (substrate).
The path radius and the relative depth are added to the clad layer (if any) because it is expected to also influence the mechanical properties.
Scratches with a small path radius can act as a stress concentrator, so they are expected to have a negative effect on the mechanical properties of parts.
Online since: October 2015
Authors: Mohammad Arif Kamal
Thermo-Physical properties of Building Elements The response of the building fabric to the outdoor environment depends upon certain thermophysical properties of the building elements.
Both these properties are wavelength dependent.
The properties of the building element are then derived from the thermophysical properties of different material layers.
Three of these properties are important in the present context.
Combinations of materials with different properties are used to provide the necessary properties in an element.
Online since: January 2014
Authors: Renata Barbosa, Dayanne Diniz Souza Morais, Tatianny Soares Alves, Osanildo Damião Pereira, Laura Hecker Carvalho
One of the best known is the PHAs poly (3-hydroxybutyrate) (PHB), a thermoplastic material which has physical and mechanical properties comparable to those of isotactic PP.
The nanoclays have been incorporated into biodegradable polymers because, besides maintaining biodegradability, they act as mechanical reinforcement and can decrease the permeability to water vapor [7-8].
Taking into account the factors set out above, and considering the great importance of nanocomposites in various applications, the present study aimed to develop nanocomposites based biodegradable polymer PHB and vermiculite clay by merge method in the molten state.
A fill factor of 70% was used in all cases and the mixer was operated at 170° C and 50 rpm for 10 minutes.
Figure 2: X-ray diffraction patterns for pure PHB and PHB Nat systems It is observed that the systems PHB Nat exhibit prominent peaks in the same region of PHB 2θ (10 to 30°), with no observed change in the crystalline structure of the polymer, this result indicates that the crystalline structure of the polymer was not affected by the addition of clay.
Online since: August 2019
Authors: Worawut Kriangkrai, Srisagul Sungthongjeen, Sirachai Leatpianpanit, Phurit Thanarangsarit, Phirawat Trirattanapintusorn
However, there are two main limitations of ODT, which are an insufficient mechanical strength i.e. hence, careful handling required and these tablets may leave an unpleasant taste and/or grittiness mouth if not formulated [2].
Although most of these medicines have efficacy or even life-saving properties, a significant portion has adverse chemosensory side effects because of an unpleasant taste [3].
The taste-masking property, physical properties, disintegration and dissolution test of ODD was performed to evaluate the factors that affect such as preparation technique, grades of crospovidone and ratio between acetaminophen and crospovidone.
The particle with a low percentage of drug release represented a taste-masking property.
The taste-masking property depended on the ratio between an active and a polymer.
Online since: March 2004
Authors: Dong Il Kwon, Ho Seok Nam, Ju Young Kim, Baik Woo Lee
Introduction Silicon carbide (SiC) is a promising material due to its remarkable properties: chemical inertness, high stiffness, hardness, toughness, optical properties, wear resistance, etc.
Even as an amorphous thin film, this material retains many of its attractive properties.
Recent developments in deposition techniques broaden the mechanical and chemical microsystem applications of a-SiC and the electrical and optical microsystem applications as well.
In addition, particular attention has been paid to mechanical stress, an important parameter in such mechanical applications of a-SiC as microelectromechanical systems (MEMS), nano-coatings, masking material in Si micromachining technology, etc.
Since thermal stress by the mismatch of coefficients of thermal expansion is not as powerful on the MD simulation scale as on the practical experimental scale [8], we ignore the influence of this factor.
Online since: October 2011
Authors: Zhen Qiang Ni, Ji Ming Kong, Fa You A
Research the Excavation Angle Affect on Seismic Dynamic Response of Slope A Fa-you1,a , KONG Ji-ming2,b, NI Zhen-qiang2,c 1 Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming Yunnan 650093, China 2Institute of mountain Hazards and Environment,Chinese Academy of Sciences, Chengdu Sichuan 610041, China aafayou@163.com Keywords: seismic dynamic response, excavation angle, slope Abstract.
Slope excavation is one of the main factors to mutation and the seismic dynamic response to earthquake mountain disasters will be different caused by different excavation angle.
Seismic activity frequent in our country western and the mountainous widespread distribution, and excavation damage slope wide distribution and quantity, a large number of casualties and property losses to the country and people caused by seismic mountain disaster of excavation damage slope.
Physical and mechanical parameters of the slope are shown in Table 1.
Table 1 Physical and mechanical parameters of the slope rock Density(kg.m-3) Elastic modulus (Gpa) Poisson's ratio granite 2,800 45 0.1 The transient dynamic analysis technology was adopted for dynamic analysis of structure.
Online since: November 2010
Authors: Yu Qing Shi
Improving the Quality in Deep Drawing of Rectangle Parts Using Variable Blank Holder Force Yuqing Shi School of Mechanical and Automotive Engineering, Zhejiang University of Science and Technology, Hangzhou, Zhejiang Province 310023, P.R.
The plastic forming of sheet metals processes experience very complicated deformations affected by process parameters such as material properties, the die shape, the blank shape, the BHF, the friction, and so on [1].
The factor ofis determined by test runs to balance the contributions of two parts in the objective function, due to wrinkling is usually at the beginning of deep drawing, in accordance with test runs, while 0.1, it is suitable to restrain the flange from wrinkling during deep drawing, but the smaller the , the larger the blank holder force to be needed, too large blank holder force can cause tearing, therefore, usually equal to 0.1.
Mechanical properties and its parameters of 08Al are indicated as follow: Young’s modulus ()=206.8 GPa, yield stress ()=110.3 MPa, Poisson’s ratio ()=0.3, strength coefficient (K)=537 MPa, strain-hardening exponent (n)=0.21, coefficient of normal anisotropy (r)=0.18.
Online since: October 2014
Authors: Laurenţiu Slătineanu, Ana Bădănac, Vasile Manole, Gheorghe Bosoancă, Dragoș Hodorogea
Thus, there are: a) Direct methods: these are methods based on using a cutting drilling process for determining a machinability index; b) Indirect methods: these are methods of performing tests which do not involve a cutting process or where analysis of various physical and/or chemical properties allows formulating comments on the behavior of the analyzed material during drilling [3].
This scheme is characterized by the same disadvantage of possible affecting test results by chips accumulated in spaces between drill tool and test piece.
Value number NVj for each of the analyzed solutions j corresponds [9] to relation: Nvi=KijKi, (2) where factors Kij are the significance coefficients of each of the solutions a, b, c, d, e, determined successively for each of the criteria A, B, C, D, E, F, and Ki are significance coefficients.
Solution Criterion A Criterion B Decision Sum of positive decisions Nj Significance factor Decision Sum of positive decisions Nj Significance factor 1 2 3 1 2 3 a 1 0 1 0.2 0.5 1 0.5 0.3 b 0 0.5 0.5 0.1 0.5 0.5 1 0.2 c 1 1 2 0.4 0.5 1 1.5 0.3 d 0 1 1 0.2 0 1 1 0.2 e 0.5 1 1.5 0.3 1 1 2 0.4 Solution Criterion C Criterion D Decision Sum of positive decisions Nj Significance factor Decision Sum of positive decisions Nj Significance factor 1 2 3 1 2 3 a 0.5 0 0.5 0.1 0.5 0 0.5 0.1 b 0 1 1 0.2 0 0.5 0.5 0.1 c 1 1 2 0.4 0 1 1 0.2 d 0 0 0 0 0 0.5 0.5 0.1 e 0 1 1 0.2 0.5 0.5 1 0.2 Solution Criterion E Criterion F Decision Sum of positive decisions Nj Significance factor Decision Sum of positive decisions Nj Significance factor 1 2 3 1 2 3 a 0 0.5 1 0.2 0.5 1 1.5 0.3 b 0 0 0 0 1 0 1 0.2 c 0 1 1 0.2 1 1 1 0.2 d 0 0 0 0 0 0.5 0.5 0.1 e 0.5 0.5 1 0.2 0.5 0.5 1 0.2 For each of the solutions a, b, c, d, e, value numbers are: Nva=0.2×0.133+0.3×0.066+0.1×0.033
Structure of equipment for evaluation of the machinability by drilling under constant force feed Conclusions A method of evaluating machinability by drilling which considers the mechanical charge generated by machining process is the drilling method under constant force feed.
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