INFLUENCE OF THE SWEEP ANGLE OF THE CROSS KNIFE OPENER ON SOIL DISTURBANCE

The cross-slot opener is a new type of seeding opener. The sweep angle, which is a key structural parameter of the cross knife, has an important influence on soil disturbance. In this paper, discrete element method and tracer method are used to study the conditions of working speed of 0.83m/s and ditching depth of 130mm, the sweep angles of the transverse knife are 0°, 10°, 20°, 30°, 40°, respectively. The influence of time opener on soil disturbance and working resistance. The simulation analysis of the operation process of the cross groove opener shows that the trenching process under different sweep angles of the transverse knife is basically the same, and the standing knife is the main cause of soil disturbance; both the tracer method and the simulation results show the surface and shallow soil particle disturbance. The proportional and horizontal working resistance first decrease and then increase with the increase of the sweep angle of the cross-slot opener. When the sweep angle of the cross-slot opener is 20°, the micro-disturbance of soil particles and the horizontal work resistance are the least; The relative error of the soil disturbance ratio obtained by the tracer method and the discrete element method are both within 15%, and the relative error of the horizontal working resistance is 6.5%. The established discrete element simulation model can more accurately simulate the soil disturbance process of the cross-slot opener.

DEFORMATION AS A PREPARING PROCESS FOR DESTRUCTION

Actual mining is accompanied with stress increasing and as a result increasing of developed space causes to deformation of rock with specialties, which brake the symmetry, obtained after statistic calculation. For horizontal working classic approach leads to calculation of symmetric relatively coordinate axes deformation. In that case boundary conditions and mechanical quantities, related to soling containing development, are sized in an arbitrary way. However, it is well known from in-situ observations that braking the symmetry and as a result caving starting happen in the most stressed point. According to used physical and mechanical laws, destruction occurs quite unpredictable and does not have single before determined behavior. As it supposed in the context of symmetric calculation, trying certainly carry out the destruction. Kinematic calculation of displacements, considering weight of rocks, has allowed to brake classic symmetry at calculation of roof and floor displacements and to get closer to understanding of mechanism of the deformation process. In the work isotropic solid with horizontal sunken working, which provides the most deformation symmetry at classic calculation, is considered. Introduction into consideration of dynamic of process of actual mining totally destroys built symmery of possible deformation providing destruction starting in the most stressed point. Dynamic is considered after single advance of support, sum of which additionally provides absence of the symmetry in the destruction process.

The Matrix of Communication in Social Movements

Communication technology has played a central role in the last two great socio-political uprisings in Iran’s history: The 1979 Revolution and 2009 Green Movement. By identifying three distinct elements of the communication process, this paper explores how the ability of the political opposition to communicate effectively contributed to the success or decline of these movements as one factor among a broader set of key factors. The first element is the ‘mainstream media’, which is professional, hierarchically structured and often funded by states, big corporations or major publicly funded organizations. ‘Alternative media’, in contrast, is amateur, has a participatory and horizontal working structure and often limited funding. The third, the ‘social network’, is a collection of actors who seek iterative and persisting exchanges among themselves based on common interests, beliefs, and other ties. This trinity constitutes what has been called the ‘matrix of communication’ in this paper.

UG and VERICUT-Based Processing of Special-Shaped Stone Samples

In order to verify the processability of a special-shaped stone machining center’s horizontal working portion, to process complex stone products. On the basis of analysis of the physical characteristics of diamond cutting tool and stone, create a model and use UG software to program, making this machine center’s dedicated post processor. Simulate NC code that is generated with VERICUT software, optimize the cutting parameters and analyse its surface quality. Avoid interference in the program, gouge, collisions and other phenomena by adjusting the tool axis’s attitude and the tool paths. Actual process verified the reliability of the program, technological parameter is rational, quality of the parts’ surface is well. Make precisely outline and tool wear is small, overcome the drawbacks of CNC system, get a higher efficiency.

Comparative Analysis of the Retrosigmoid and Lateral Supracerebellar Infratentorial Approaches along the Lateral Surface of the Pontomesencephalic Junction: A Different Perspective

Objective: To quantitatively assess the working distance and angle of attack among the retrosigmoid (RS), lateral supracerebellar (LS), and extreme lateral supracerebellar (EL) views on the lateral surface of the pontomesencephalic junction. Methods: Eight sides of silicone-injected fixed cadaveric heads were dissected using the three approaches. All predetermined anatomic points were collected by use of a frameless stereotactic device. The length of exposure and the angle of attack were calculated and compared. Predissection imaging was obtained for illustration. Results: The LS and EL approaches created a horizontal working space as compared with the vertical working space created by the RS approach. The RS view gained less posterior exposure margin than the LS and EL views (posterosuperior margin values: RS, 4.3 ± 1.7 mm; LS, 6.4 ± 2.0 mm; EL, 7.3 ± 2.0 mm; P < 0.001; posteroinferior margin: RS, 2.7 ± 2.7 mm; LS, 4.9 ± 2.8 mm; EL, 8.3 ± 2.5 mm; P < 0.001). When the tentorium is intact, transverse sinus retraction significantly accentuates the field of view by the EL approach compared with the LS approach at both the anteroinferior (P < 0.05) and posteroinferior (P < 0.001) margins. Between the supracerebellar types, the vertical angle of attack was significantly improved and the horizontal angle was significantly decreased when complete venous retraction was performed. Conclusion: The supracerebellar views offer greater advantage over the RS view when the surgeon is working more posteriorly on the pontomesencephalic junction. Between the supracerebellar views, venous retraction creates a significantly wider vertical angle and also improves the exposure when the surgeon is working more inferiorly.

Lighting controls in areas with innovative daylighting systems: a study of sensor type

Innovative daylighting systems often work by redirecting light from the sky and sun onto the ceiling from where it is diffused to light the space. This can cause problems for ceiling mounted photoelectric control sensors. The performances of three types of ceiling sensor were studied in the Building Research Establishment’s mock-up rooms. The window systems included venetian blinds, prismatic film and a light shelf as well as ordinary clear glass. A completely unshielded sensor gave surprisingly stable performance compared with horizontal working plane illuminance. The main exception to this was when direct sunlight reached the sensor itself. Unfortunately the ratio of sensor illuminance to horizontal illuminance was significantly greater under sunny skies than under overcast skies. This could lead to uneven control performance under different sky conditions. An alternative sensor shielded by a darkened tube was also tested. This proved to be very susceptible to the location of patches of sunlight in the space. In a real room it could also be affected by the positions and reflectances of furniture and even occupants. A possible compromise is the use of a partially shielded sensor. This can receive light from all directions except the window. Care is needed in aligning the shield correctly during installation.