CHARACTERIZATION OF ANATOMICAL, MORPHOLOGICAL, PHYSICAL AND CHEMICAL PROPERTIES OF KONAR (ZIZIPHUS SPINA-CHRISTI) WOOD

The goal of this research is to investigate some morphological (fibre length, fibre diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, slenderness coefficient, rigidity coefficient, Luce's coefficient, solid coefficient), physical (dry wood density, volumetric shrinkage) and chemical (cellulose, hemicellulose, lignin, ash and acetone soluble extractives contents) composition of Konar (Ziziphus spina-christi) wood grown in Hormozgan province, Iran. For this purpose, three normal trees were selected randomly and a disk was cut from each one at breast height. Anatomical inspection revealed that the species was diffuse porous, with distinctive growth rings, simple preformation plate, with polygonal openings, and banded or diffuse-in aggregates parenchyma. The average values of wood dry density, fiber length, fiber diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, felting coefficient, Luce’s coefficient, solid coefficient, rigidity coefficient were 0.926, 52.1, 77.85, 0.57, 163 ×103 μ3 and 0.48. Cellulose, hemicellulose, lignin, acetone soluble, extractives, ashcontents were43.34, 19.98, 33.9, 6.42 and 2.78%, resp.

MORPHOLOGICAL PROPERTIES OF HURA CREPITANS L. (EUPHORBIACEAE) AS PROSPECTIVE RESOURCE FOR PULP AND PAPERMAKING

Hura crepitans L. (Euphorbiaceae) is a tropic tree species that was investigated for pulp and paper characteristics in this study. The diameters of five (5) different stands of Hura crepitans trees were first determined using diameter tape. Wood slivers were obtained from sapwood of the trees parallel to grain and at three (3) different positions along the axis, at the base (5%), middle (50%) and top (90%). The wood slivers were macerated in a mixture of equal volumes of glacial acetic acid and hydrogen peroxide at between 80 -100 degrees Celsius for 2 hours. Macerated fibres were washed and used to prepare microscopic slides where 15 fibres were measured per slide. Data recorded was subjected to One-way Analysis of Variance (ANOVA) based on Completely Randomized Design (CRD). Results show that both the primary fibre characteristics and derived characteristics were significantly different at p<0.05? The mean fibre characteristics ranged as follows, Fibre lengths (0.87-1.16 mm), Fibre diameter (18.84 - 24.44 µm), Lumen width (9.92-16.89 µm) and Cell wall thickness (3.93-4.60 µm). The derived mean fibre characteristics ranged as follows; Runkel ratio (0.36-0.78), Elasticity coefficient (44.20-67.91%), Rigidity coefficient (15.98-27.82 %) and Slenderness ratio (0.44-0.80). This result implies that Hura crepitans has short fibres with high flexibility, which can collapse easily and form a fully bonded paper and is therefore recommended for pulp and paper production

Research and improvement of methods of testing machines for geometric and kinematic accuracy

Purpose. To analyze and check for adequacy the known calculation formulas in determining the geometric and kinematic accuracy, statistical and dynamic rigidity and testing the machine for technological reliability. To carry out comparative calculations to simplify the methodology of complex tests of metal-cutting machines of the universal group. To select and improve the measuring equipment during the complex tests of the milling machine. Methodology. The research is based on the use of analytical methods for calculating the static rigidity coefficient, additional calculation of the measuring instrument design due to the gear ratio, the angle of rotation of the lever and the theoretical error of the displacement mechanism based on the known probability distribution theorem. Findings. The formulas of researches of the coefficient of static rigidity, the mechanism of the measuring device, the angle of rotation of the lever, the theoretical error of the mechanism of movement and the density of probability of distribution of the angle of the lever mechanism of the indicator of tangent type has been obtained. Originality. The research has been carried out and the parametric relationship between the static rigidity coefficient in the design of the spindle assembly of the vertical milling machine with the error of the calculations of the design, the departure of the spindle cone and the location between the supports has been established. The values and functional dependences of the amplitude of oscillations on the maximum allowable spindle speeds and feed rates at which the surface roughness of the workpiece reaches the specified geometric limits has been obtained. It is experimentally confirmed that the parameters of the system of pre-planned repairs are directly related to the reliability of the machine. The resource on the accuracy of the machine determines the need for overhaul, and the repair period depends on the service life of parts and elements of the machine. The actual service life should be a multiple of the repair period, as the restoration of the part is planned during the current repair. Practical value. The practical achievement of the obtained results is to confirm the adequacy of the known calculation formulas in determining the geometric and kinematic accuracy, statistical and dynamic rigidity and testing the machine for technological reliability. On the basis of the received analytical and settlement data was made the simplified complex technique of test of the metal-cutting machine during the: testing the machine at idle; testing of the machine when working under load; testing of the machine for geometric and kinematic accuracy; determination of statistical and dynamic rigidity; research of vibration-resistant vertical milling machine; testing of the machine for technological reliability.

Deeper insight into the morphological features of sunflower stalk as Biorefining criteria for sustainable production

Effective utilization of fibrous materials plays a major role in techno-economic viability of the resources. Sunflower stalk (SS) as one of highest bio-fibrous waste was assessed respect to fiber features in biorefinery approach. The lumen diameter, wall thickness and fiber length were measured as (∼12 µm), (5.25 µm) and (1.58 mm), respectively. The wider lumen diameter makes its suitable for chemical treatments and purification. The applied Pulping conditions decreased the fiber length and wall thickness, with the least reduction by soda-anthraquinone. Derived indices involved rigidity and flexibility coefficients, aspect and Runkel ratios, solid and Luce’s shape factors were also calculated based on the measured values. The aspect ratio (77.5) put SS fibers as very good resources for lignocellulosic products and composites. The flexibility coefficient (57) belongs to the elastic category and was not altered by pulping. The Runkel ratio was lesser than 1 (>0.9) but decreased by the pulping, to some extent. The Luceʼs shape factor was nearly calculated 0.5, near to the bagasse and eucalyptus species. Solid factor (0.17) and rigidity coefficient (0.51) were considered to be good fiber resource. Totally due to the SS fiber characteristics, the agricultural waste suitability for value adding bio-based production could be reported.

Effective Shank Length of Bolts Under Lateral Loading

Additional lateral load tests, with improved techniques, were conducted on M22 stainless bolts to supplement the series of metric system stainless bolt tests which were conducted previously. Using the strain gage-deflection data collected from the entire set, i.e., of different sizes and different lengths, of the bolt tests, the “rigidity coefficient”, which is used in calculating the deflection of the bolts under lateral loads, using the conventionally assumed effective shank length, is derived. Alternatively, a new analytical effective shank length, which is more accurate than the conventional assumed effective shank length, derived from the test data, is proposed.

STUDYING THE INFLUENCE OF MECHANICAL AND ELASTIC PROPERTIES OF DEADWOOD BEARINGS ON RIGIDITY COEFFICIENT NUMERICAL VALUE

The article studies the influence of a rigidity coefficient of the elastic supports and a foundation, which simulate deadwood bearings in the design models, on the stress-strain state of the ship shaft line. The importance of a rigidity coefficient in designing the ship shaft line and its elements has been specified. In the analysis the rigidity coefficient is taken as a constant value. Elastic characteristics of the stern bearing bushings may greatly affect the parameters of the designed shaft lines. Generally, the stern bearings are made of caprolon, pockwood, babbit and rubber. There has been presented a design model of the ship shaft line on elastic point support. It has been stated that the value of the rigidity coefficient is specified in many works when calculating the ship shaft line, but there is no reference to the sources and methods of receiving it. The overall view of the deformed contact of the shaft with stern bearing has been illustrated. The technique of determining the rigidity coefficient has been offered, subject to mechanical and geometrical parameters of the ship shaft line and its deadwood bearings. The equation of defining the stern bearing rigidity coefficient has been produced, which helps to account the elastic parameters of the bushings and geometry of contact of the ship shaft line with the bushing. For reliability of the offered technique a number of pilot studies on the hydropress П-125 were conducted, for which there were manufactured special devices and a mandrel. The essence of method of determining a rigidity module, according to GOST 9550-81, is in measuring the ratio of stress increment to a corresponding increment of relative deformation of compression. It was proved that the divergence of the values of rigidity coefficient received by the experimental and theoretical ways does not exceed 8%.

Biomechanics of the corneoscleral shell and hemodynamics of the glaucomatous eye: is there a connection?

Purpose. To find the connection between the parameters of the corneoscleral shell and lamina cribrosa (LC) and hemodynamic parameters of the eyes with primary open angle glaucoma (POAG).Materials and methods. The study involved 111 eyes of 63 patients, including 41 eyes without ophthalmic pathology (control group, mean age M ± SD 66.9 ± 18.2 yrs), 22 eyes with the initial glaucoma stage (group 1, mean age 65.9 ± 11.3 yrs), 31 eyes with the developed glaucoma stage (group 2, mean age 69.2 ± 17.3 yrs), and 17 eyes with the advanced glaucoma stage (group 3, mean age 69,7 ± 7.3 yrs). LC parameters and the density of surface (SVL) and deep (DVL) vascular layers were measured using Spectralis OCT2 with an angiography module (Heidelberg Engineering, Germany) in the enhanced deep imaging (EDI) mode using AngioTool software. Corneal hysteresis (CH) and corneal resistance factor (CRF) were determined using ORA (Ocular Response Analyzer, Reichert, USA). The rigidity coefficient (E) of the corneoscleral shell was measured by a GlauTest-60 tonograph (Russia) operation in the differential tonometry mode. The elasticity coefficient (s) was determined by a modified differential tonometry technique. The rheographic index (RI) and pulse blood volume (PBV) were measured using transpalpebral rheoophthalmography.Results. A statistically significant correlation was revealed between CH and SVL (р = 0.005, r = 0.288), LC thickness and SVL and DVL (р = 0.001, r = 0.374 and р = 0.003, r = 0.397, respectively). A negative statistically significant correlation was found between E and RI (р = 0.000, r = -0.538) as well as between E and PBV (р = 0.001, r = -0.376). A similar correlation was revealed between s and theses parameters (RI and PBV; р = 0.027, r = -0.404 and р = 0.024, r = -0.410, respectively). E increase is accompanied by a decrease in the SVL density (р = 0.000, r = -0.376); besides, PBV is negatively correlated with the LC depth (р = 0.022, r = -0.257).Conclusion. In POAG, deteriorated blood supply of inner ocular shells (decreased RI, PBV, SVL and DVL density) correlates with (a) increased corneoscleral rigidity (manifested in the increase of rigidity and elasticity coefficients, and the decrease of CH), and (b) decreased LC thickness and its increased depth. Increased rigidity of the corneoscleral shell contributes to an LC posterior displacement. It must be concluded that LC thickness is a more sensitive biomechanical parameter that changes even in the initial stages of POAG and has a high diagnostic value.

Load-bearing capacity and characteristic forms of destruction of furniture joints made with rastex 15 and P-10 clamex fasteners

Load-bearing capacity and characteristic forms of destruction of furniture joints made with rastex 15 and P-10 clamex fasteners. The study tested the relationship between the load and angular deflection in furniture joints. The tests were carried out for two types of fasteners and five types of materials: chipboard, MDF, hardwood plywood, glued pine boards and glued oak boards. The furniture joint samples contained two fasteners preloaded only with a bending moment (without application of shear forces). The results were converted per single fastener specifying: its maximal load capacity, 50 mrad (2.9°) limit deflection and rigidity coefficient. It was found that rigidity is a better structural property of the tested joint types than their load capacity. As far as rigidity is concerned, the most durable is the combination of oak glued board – rastex 15 fastener (13.2 Nm bending moment per fastener), while the least durable combination is chipboard – clamex P-10 fastener (4.8 Nm bending moment per fastener). Photographic documentation of damaged furniture joint samples was prepared and analysed. In case of chipboard and MDF combinations (where the load is determined by the combined material), the combined boards suffer a disastrous damage, while in combinations of plywood boards and pine or oak glued boards, (where the capacity is determined by the fastener), both clamex P10 and rastex 15 fasteners are damaged.

INFLUENCE OF MATERIAL OF DEADWOOD BEARINGS ON FREQUENCY OF CROSS FLUCTUATIONS OF THE SHIP SHAFT LINE

The article describes the ship shaft line which is a constructive complex linking kinematically the main propulsion engine to the thruster and designed to pass torque moments and axial loads, appearing in the operation process of the ship propulsion system. Service life of the ship shaft line depends on operational condition of stern bearings in the shaft tube, that is why they should have high resistance against actual loads and preserve operational characteristics. There is studied the influence of elastic properties of stern bearings on numerical value of eigen frequency under cross oscillations if the ship shaft line. Assessment of influence of the deadwood bearing material on the rigidity coefficient is made. The settlement scheme for studying cross fluctuations represents a beam with constant cross section that leans on one hinged immovable elastic support with a rigidity coefficient c . At the end of a beam there is a concentrated load. The elastic support and the concentrated load model the stern bearing and the propeller screw, respectively. The technique of determining the rigidity coefficient subject to mechanical and geometrical parameters of the ship shaft line and its deadwood bearings is described. The importance of the numerical value of the rigidity coefficient of different materials of plugs of deadwood bearings when calculating cross fluctuations of the ship shaft line has been estimated. The real ship shaft line is investigated.