Sufficient Rigidity Research Articles

A basic study on levitation characteristics of metal foil by edge-supported electromagnetic levitation system

The grasping and conveying of an object by utilizing the frictional force generated by contact are performed during various steps in the process of manufacturing industrial products. Deterioration of the surface quality due to these contacts is a problem. A noncontact way to transport steel plates using electromagnetic force has been proposed as a solution to these problems. In such applications to date, electromagnets are installed in the vertical direction. However, if the steel plate is thin and lacks sufficient flexural rigidity, it is difficult to exert enough suspension force to levitate the entire steel plate. To solve this problem, we propose an edge-supported electromagnetic levitation system suitable for flexible steel plates using electromagnets installed in the horizontal direction. In this paper, we report on levitation experiments to verify the effectiveness of the proposed system and discuss characteristics of the horizontal positioning of electromagnets and levitation suspension.

Verification of stiffness and surface treatment of axial bearing levers by static tests

To eliminate misalignment between stator and rotor (especially in large rotary machines) the thrust bearing with a system of very precise manufactured levers has started to be used. The article deals with the static tests of self-equalizing elements (levers) made of 34CrNiMo6 steel, which are the critical parts of a newly developing self-equalizing thrust bearing. To verify the stiffness of the newly designed levers by static tests, the real levers were produced, which according to preliminary experiments and numerical simulations have the potential to be used the most in turbines. Based on basic tests of the pairs samples, that represent types of geometries going in contact within real conditions, it was found out that in terms of the surface treatment, the best results show electroless nickel-plated samples. So, due to this reason, the real levers were produced and their surfaces were processed in this way by electroless nickel-plating. Within the presented research, they were statically tested intending to determine the surface integrity and whether there was any development of damage to the surface layer. The evaluation was done using a stereomicroscope and a scanning electron microscope. The tests confirm sufficient rigidity of the levers including a suitable method of surface processing. Although, in some cases, these were surface defects caused by surface treatment technology, but no defects were found after static loading.

ПРИМЕНЕНИЕ МЕТОДА «КОНЕЧНОГО ПОВОРОТА И СМЕЩЕНИЯ» В УПРАВЛЕНИИ ПАРАБОЛИЧЕСКОЙ АНТЕННОЙ

The article deals with the application of the "finite rotation and displacement" method (FRDM) which can find the desired values of the generalized coordinates for the control system of a parabolic antenna. The special manipulator of a sequential structure with sufficient rigidity is used to control the parabolic antenna. The rigidity of this manipulator is ensured by use of links in the form of spherical shells and bearings located along the perimeter of each shell in the rotation plane of each link. It allows to optimally place the material of the manipulator's design and to obtain sufficient rigidity with minimal weight. The manipulator consists of four links connected by fifth class kinematic pairs with an arbitrary inclination of the axes. For this task the antenna's orientation is important without taking into account the small displacement of its position during the process of its orientation. The FRDM method provides both orientation and position. It is based on determining the precise and optimal iterative steps for each degree of mobility, providing maximum approximation to the specified orientation parameters of the parabolic antenna. According to the method's algorithm, the software is developed consisting of subprograms for organizing a general solution of the inverse kinematics for an arbitrary number of links and a particular one for a manipulator in the form of source data. The initial data are the vector model of the manipulator, the values of the structural constraints of the generalized coordinates, and the characteristics of kinematic pairs by type and class

Microstructure and Properties of the Nitrided Layer of Nodular Cast Iron

Abstract The plunger pair is an important part of the plunger pump. It is required to have high wear resistance, self-lubrication, deformation resistance, and sufficient strength and rigidity because of the harsh application environment, thus ductile iron is a common material for large piston pumps because of its excellent overall performance. In order to improve the friction and wear performance of spheroidal graphite cast iron plungers, a nitride layer was prepared on the ductile iron QT600-3 by the ion nitriding technique. The morphology of the permeable layer was observed with a metallographic microscope, and its hardness, friction, and wear properties were analyzed using a Vickers hardness tester and a multifunctional material tester. The results of the article show that the hardness of the nitrided specimens is greatly improved, which is about twice the hardness of the matrix. The friction coefficient is found to be much lower than the friction coefficient of the matrix; the diameter of the wear scar is small, showing a moderate change compared with the matrix; and the performance is about four times. Therefore, the ion nitriding technique can significantly improve the friction and wear resistance of the pump plunger pair.

Technological Structures for Air Cooled Condensers

This paper summarizes the knowledge and results obtained in the field of designing technological platforms for energy industry. Optimal solution of the layout of elements and material of a number of technological platforms with a specific number of modules was searched. Technological platforms are the main supporting structure of the air-cooled condensers (ACC), which ensure cooling of plants. The fundament of the solution is based on the schema that the platform is composed from the at least one standardized bed containing the supporting surface equipped with the supporting columns and at least one horizontal segment for the condenser exchanger support. The platform structure must ensure sufficient spatial rigidity and stability and ACC functionality. Design requirements are defined both by size and weight of each single module of condenser and the total number of modules in assembly.

Technological Structures for Air Cooled Condensers

This paper summarizes the knowledge and results obtained in the field of designing technological platforms for energy industry. Optimal solution of the layout of elements and material of a number of technological platforms with a specific number of modules was searched. Technological platforms are the main supporting structure of the air-cooled condensers (ACC), which ensure cooling of plants. The fundament of the solution is based on the schema that the platform is composed from the at least one standardized bed containing the supporting surface equipped with the supporting columns and at least one horizontal segment for the condenser exchanger support. The platform structure must ensure sufficient spatial rigidity and stability and ACC functionality. Design requirements are defined both by size and weight of each single module of condenser and the total number of modules in assembly.

U Tipi Plan Düzensizliği olan Betonarme Yapılarda Perde Yeri Seçiminin Yapısal Davranışa Etkisinin İrdelenmesi

Damage to structures may occur due to irregularities and other effects on reinforced concrete structures. Due to the earthquake zone, the buildings to be designed in our country should be designed according to the earthquake loads. In this study, the effects of the location and directions of the shear walls on the earthquake loads in the case of discontinuity in reinforced concrete buildings were examined. In this study, the effect of curtain placement on structural behavior in reinforced concrete buildings with U type plan irregularity was investigated.In order to determine the behavior of the structure under the effect of the earthquake and to find the relevant cross-sectional effects, the regular or irregularity of the structure of the structure of the structure is significantly effective. Irregularities present in the design cause further strain of the carrier elements. With the increase in the number of floors in earthquake risk regions, curtains are needed in order to ensure sufficient rigidity and strength in the frame systems and to limit the floor displacements. When the shear walls are used together with the frame system in a conveyor system, their stiffness is larger than the columns and they meet a significant part of their horizontal loads such as earthquake and wind.In this study, the effect of shear walls placement on structural behavior in reinforced concrete buildings with U-type irregularity was investigated. For this purpose, 7 models, each of which are 5,10,15 stories and one of which are reference models, have been examined on the irregularity and behavior of the structure in different shear walls settlements. The results obtained by using the İDECAD V7 program were compared with the results analyzes were made using the principles of TBDY 2018 and the results were reached.

H Tipi Plan Düzensizliği olan Betonarme Yapılarda Perde Yeri Seçiminin Yapısal Davranışa Etkisinin İrdelenmesi

Due to various architectural and structural requirements, irregularities in the structures are inevitable. In order to determine the behavior of the structure under the effect of the earthquake and to find the relevant cross-sectional effects, the regular or irregularity of the structure of the structure of the structure is significantly effective. Irregularities present in the design cause further strain of the carrier elements. With the increase in the number of floors in earthquake risk regions, curtains are needed in order to ensure sufficient rigidity and strength in the frame systems and to limit the floor displacements. When the shear walls are used together with the frame system in a conveyor system, their stiffness is larger than the columns and they meet a significant part of their horizontal loads such as earthquake and wind. In this study, the effect of shear walls placement on structural behavior in reinforced concrete buildings with H-type irregularity was investigated. For this purpose, 7 models, each of which are 4,8,12 stories and one of which are reference models, have been examined on the irregularity and behavior of the structure in different shear walls settlements. The results obtained by using the İDECAD V7 program and DBYBHY-2007 principles ware analyzed by using 2018 TBDY for 4 storey models from the results found using Sap2000 program and the results were compared. The buildings were evaluated among themselves according to the reference model withhout plan disorder.

Does erectile dysfunction improve the assessment of cardiovascular risk?

Erectile dysfunction (ED) is defined as the inability to obtain or maintain sufficient penile rigidity for sexual satisfaction (1), which can create a psychological strain and become a distressing condition for men (2). It is estimated that ED affects 150 million men in the world and approximately 30 million in the United States alone (1).

Structural Evaluation of Torsional Rigidity of New FRP–Aluminum Space Truss Bridge with Rigid Transverse Braces

A unique fiber-reinforced polymer (FRP)–aluminum spatial truss structure with upper I-type, transverse beam braces was developed for deployable bridging, yielding the operational advantages of bestraddled erection bridges. Experimental testing and numerical simulation were performed to evaluate the torsional rigidity of a fabricated cantilever, full-scale experimental structure. The predictions obtained based on a computational finite element model were strongly consistent with the experimental results. Moreover, a numerical decomposition and reconstruction procedure was employed to understand the load-bearing mechanism of the structure. The results demonstrated that the improved transverse braces possessed adequate capacity for providing sufficient rigidity and lateral stability to the complete twin-treadway structure under torsion. The torsional center of the improved structure was located at the axis of symmetry of the twin-treadway bridge deck. The representative torsional rigidity of the twin-treadway module was approximately 87.5 kN·m2/degree. Compared to the original construction, the improved structure exhibited only minor discrepancies regarding the torsional rigidity, and consistent characteristics in terms of the load-bearing mechanism. The torsional rigidity of the improved twin-treadway structure was primarily generated by the vertical bending rigidities of its two parallel single treadways through the rigid transverse braces. This significant finding specifically pertains to the unique twin-treadway hybrid bridge. The results presented in this work are expected to provide valuable insights, which could, in turn, lead to further the development of similar lightweight structural systems.

Mechanical Design Concept of Superconducting Magnet System for Helical Fusion Reactor

The conceptual design of a helical fusion reactor was studied at the National Institute for Fusion Science in collaboration with other universities. Two types of the force free helical reactor (FFHR) are FFHR-d1 and FFHR-c1. FFHR-d1 is a self-ignition demonstration reactor that operates with a major radius of 15.6 m at a magnetic field intensity of 4.7 T. FFHR-c1 is a compact subignition reactor that aims to realize steady electrical self-sufficiency. Compared to FFHR-d1, FFHR-c1 has a magnetic field intensity of 7.3 T and a geometrical scale of 0.7. The location of the superconducting coils in both types of FFHR is based on that of the Large Helical Device (LHD). LHD has a major radius of 3.9 m. According to the design of LHD, the deformation must be within the required value to compensate for the accuracy of the magnetic field. According to this concept, the magnet support structure of LHD was fabricated using thick Type 316 stainless steel to impart sufficient rigidity. Thus, the stress of the magnet system of LHD is sufficiently below the permissible stress. In the case of FFHR, from the viewpoint of the reactor, a large access port is required for the maintenance of the in-vessel components. The mechanical design of the support structure is conceptualized by considering the basic thickness of the material and residual aperture space by referencing the mechanical analysis results. Details of the design concepts of LHD and FFHR-d1/FFHR-c1 as well as the results of mechanical analyses are introduced in this paper.

Современные упаковочные решения для концентрата сывороточных белков

The competent choice and use of packaging materials is one of the most urgent tasks of the dairy industry, i.e. the feedstock; production technology and applied processing; organoleptic characteristics of the product; its weight; conditions, modes, and duration of transportation, storage, and sale. There is a long list of requirements for packaging materials in dairy industry. It includes high strength, resistance to wear, sufficient rigidity, an ability to weld; formation of strong and sealed seams; an aesthetic design that can attract the consumer; standard labeling, etc. The present article features the objectives and requirements of packaging; types of packaging; innovative technologies used for packaging whey protein concentrate and its products; modes and conditions of transportation and storage. Today, Russian packaging manufacturers have developed and mastered a wide range of packaging materials, closures, transport and consumer packaging of domestic raw materials; innovative packaging technologies for dairy products that take into account the sensory, structural, and mechanical characteristics of packaged products; the timing of implementation and storage. The main prospect is the development and production of packaging materials with an improved and predictable set of safety indicators and barrier level, e.g. multilayer and combined materials, such as polymer, based on innovative technological solutions.

Projectile impact on fabric-metal assemblies – Influence of fabric-metal sequence

Fabrics woven from high-strength fibres are increasingly employed for protection against projectile impact, because of superior mechanical properties. In some applications, high-strength fabrics are combined with metallic components to provide sufficient structural rigidity and strength – e.g. for vehicle bodies, turbine engine fragment barriers, building doors, etc. An understanding of how the fabric-metal layer sequence affects the resulting ballistic resistance, is essential for effective design of such fabric-metal assemblies. This motivates the current study, whereby multiple plies (1, 2 or 4) of Twaron (T) aramid fabric were combined with an aluminium alloy (A) thin plate to form a lightweight protective panel. The projectile impact penetration resistance of three types of fabric-metal arrangements were examined – i) the aluminium alloy plate as the impact face; ii) the Twaron fabric as the impacted layer; iii) the aluminium alloy plate sandwiched between fabric layers. For assemblies with a smaller number of fabric plies (i.e. 1 or 2), siting the aluminium alloy plate as the rearmost layer results in a significantly higher impact energy absorption capacity, compared to having the aluminium alloy plate as the impact face – e.g. for (A+1T) assemblies, i.e. Al plate+1 ply of Twaron, 1T/A (impact face layer appears first in this nomenclature) performs much better than A/1T. For (A+2T) assemblies, 2T/A provides the highest impact resistance, A/2T is the weakest, and 1T/A/1T lies in between. However, when the number of fabric plies is increased to 4, a variety of responses was observed. An A/4T configuration absorbs significantly higher energy than a 4T/A arrangement, while a symmetrical 2T/A/2T sequence absorbs less energy than either an A/4T or 4T/A configuration. High-speed optical photography images and post-test specimens were analysed, to examine the deformation and failure modes of the fabric plies and Al plate in the fabric-metal targets, and how they are affected by the fabric-metal sequence. These help identify the interaction between the fabric plies and Al plate for various fabric-metal sequences, in order to account for the phenomena observed in experiments.

Numerical Analysis and Effects on Rigidity of Combat Vehicle Structure Due to Blast Load

Blast effects are severe especially in case of close underbelly blast events. The hull of the structure must resist the blast load with limited deformation and on the other hand it should have sufficient rigidity also to have optimised structural design. Numerical analysis revealed the peak deformation areas on the hull structure which were further stiffened by adding the stiffeners to control the peak deformation. In the analysis, the stress-time, pressure-time and deformation-time graphs were also obtained for the blast events for with and without adding stiffeners. The optimised plate thickness with limited deformation by means of stiffeners was obtained.

Cavernosal artery peak systolic velocity among normal adults in Abuja, Nigeria: A Baseline parameter for sonographic diagnosis of vasculogenic erectile dysfunction

Background: Erectile dysfunction is consistent inability to achieve and maintain erection of sufficient rigidity for satisfactory sexual performance. It is well known that the hemodynamic function of the penis correlates well with the peak systolic velocity (PSV) of the cavernosal artery (CA) which is the most reliable, sensitive, and objective parameter used in evaluating the state of the erectile tissues of the penis. This study was aimed at establishing the normal CA PSV in this environment, as it may differ from the values among Americans, Caucasians, and Asians. Materials and Methods: The study was conducted between July 2015 and January 2017, at the Department of Radiology, Federal Medical Centre, Abuja. Twenty-nine consecutive patients referred by the urologist to the radiology department of the aforementioned institution for penile ultrasound were evaluated using triplex Doppler sonography with high-frequency linear array transducer. The penile scan was done before and after intracavernosal injection of 10–20 μg prostaglandin E1. The waveforms of CAs were obtained alternately using the angle of inclination ≤60°, and the PSV of the CA was documented at 5-min interval, from 5 to 40 min. Results: PSV of CA varied between 26 and 104.4 cm/s (mean: 46.72 ± 16.21) among the entire research participants. No significant discrepancy was noted between PSV of the right and left cavernosal arteries. The PSV had a strong positive relationship with age (P = 0.002), with the highest values found among those ≤30 years. Conclusion: The mean PSV of cavernosal arteries established in this study is not significantly different from the values obtained among Americans, Caucasians, and Asians, indicating that racial difference has no effect on this important sonographic variable.

Experimental and numerical analysis of curling behavior of natural hydraulic lime - cement based mortars

This paper aims to identify the parameters influencing the curling phenomenon, and to understand the influence of cement substitution by increasing proportions of Natural Hydraulic Lime (NHL) on the kinetics and the final curling magnitude. The developed experimental approach shows that the curling is mainly driven by the progress of the drying front in the specimen depth. A common curve curling-drying depth is observed for all the studied mortars independently of their mix-design. Results also show that NHL leads to a significant reduction in the curling's final amplitude and delayed its start time due to its influence on the microstructure of studied mortars. Based on the experimental results and, mainly, on the spatio-temporal internal relative humidity evolutions, a poroviscoelastic model which incorporates well-accepted mechanisms for shrinkage is proposed. The model is able to reproduce the evolution of curling and to estimate the viscoelastic response of the studied mortars. The curling starts developing as soon as the material develops sufficient rigidity, and its magnitude is mainly related to the viscoelastic-aging modulus which is about the same for all the studied mortars.

Horticultural Homicide

Instruments that create stab wounds are required to possess tips of sufficient strength and rigidity to breach the integrity of the skin. Knives, the most common weapons used to create stab wounds, have cutting edges that cleave the skin, leaving unabraded margins. On rare occasions, blunt objects are driven with sufficient force to pierce the skin and become impaled within the body. The morphologic differences between the cutaneous injuries and wound tracks of stab wounds from sharp objects and impalement with blunt ones provide clear delineation of the two. However, elements from the scene and obscuring hemorrhage can make initial differentiation difficult. The authors report the death of a 59-year-old woman found near the entryway steps of her home with a stab wound to her chest. Law enforcement did not discover any weapons. Investigation focused on blood around and on a broken rose bush planted near the steps with the belief that the decedent had fallen upon the vegetation. When presented with information that conflicts with autopsy findings, careful consideration of proposed weapons and thorough examination of the wound are required to discount confounding material.

The Role of Revascularization of the Profunda Femoris Artery in Vasculogenic Impotence

Erectile dysfunction is a common disorder, but the underlying cause is difficult to clarify because the organic (endocrine, neurogenic, vasculogenic and iatrogenic) and psychological components are mixed. Vasculogenic impotence, due to penile vascular insufficiency, is a common symptom in patients with aortoiliac occlusive disease (Leriche’s syndrome).The aim of this clinical study was to investigate the hypothesis that revascularization of the profunda femoris artery in Leriche’s syndrome offers good results in vasculogenic erectile dysfunction. We investigated 22 men aged 50–65 years (mean 57.5 years) with vasculogenic impotence due to Leriche’s syndrome. Exclusion criteria were: age >70 years, comorbidities, such as diabetes mellitus (DM), heart failure, HIV, history of perineal trauma and medication associated with erectile dysfunction (i.e., antidepressants, anxiolytics, antiandrogenics, anticholinergics). After clinical examination, measurement was made of the angle brachial pressure index (ABPI) and the penis brachial pressure index (PBPI) with duplex ultrasonography (U/S). All the patients underwent vascular imaging: 15 digital subtraction angiography (DSA) and 7 computed tomography angiography (CTA). Psychological investigation was carried out and the papaverine test was performed to exclude other causes of impotence. The patients underwent aorto-bifemoral bypass, with profundoplasty, if needed, and were followed for one year after operation with clinical examination and measurement of the ABPI and PBPI with duplex U/S. Preoperatively, all the patients reported absence of erectile function, with inability to achieve an erection of sufficient rigidity. Clinical examination revealed absence of pulses to peripheral arteries beyond the femoral arteries and absence of bruits in the iliac arteries. The ABPI ranged between 0.35 and 0.45 (normal: 1) and the PBPI between 0.2 and 0.32 (normal: 0.75). Aorto-bifemoral reconstruction (Y-Graft) with profundoplasty, if required, was performed on all patients. In 4 patients (group I) the peripheral arteries (common, profunda and superficial femoral artery) were not affected by atherosclerotic disease and profundoplasty was not required. In 18 patients (group II) profundoplasty was necessary because of atherosclerotic occlusion of the superficial femoral arteries and stenosis of the profunda artery. Postoperatively, in group I the ABPI became normal and the PBPI ranged between 0.5 and 0.6. In group II the ABPI ranged between 0.6 and 0.75 and the PBPI between 0.48 and 0.55. During the first month of the postoperative period 14 patients (4 from group I and 10 from group II) had normal erectile function (63.6 %) and during the late postoperative period (3-6 months of follow up) 5 more patients (2 from group I and 3 from group II) had improvement of the erectile function (22.7 %). No significant clinical improvement was observed in the other 3 patients (13.6 %). In patients with Leriche’s syndrome, revascularization of the profunda femoris artery (profundoplasty) ameliorates vasculogenic impotence through the improvement of the pelvic blood flow via the collateral circulation.

3D-Printed PCL/PLA Composite Stents: Towards a New Solution to Cardiovascular Problems.

Biodegradable stents (BRS) offer enormous potential but first they must meet five specific requirements: (i) their manufacturing process must be precise; (ii) degradation should have minimal toxicity; (iii) the rate of degradation should match the recovery rate of vascular tissue; (iv) ideally, they should induce rapid endothelialization to restore the functions of vascular tissue, but at the same time reduce the risk of restenosis; and (v) their mechanical behavior should comply with medical requirements, namely, the flexibility required to facilitate placement but also sufficient radial rigidity to support the vessel. Although the first three requirements have been comprehensively studied, the last two have been overlooked. One possible way of addressing these issues would be to fabricate composite stents using materials that have different mechanical, biological, or medical properties, for instance, Polylactide Acid (PLA) or Polycaprolactone (PCL). However, fashioning such stents using the traditional stent manufacturing process known as laser cutting would be impossible. Our work, therefore, aims to produce PCL/PLA composite stents using a novel 3D tubular printer based on Fused Deposition Modelling (FDM). The cell geometry (shape and area) and the materials (PCL and PLA) of the stents were analyzed and correlated with 3T3 cell proliferation, degradation rates, dynamic mechanical and radial expansion tests to determine the best parameters for a stent that will satisfy the five strict BRS requirements. Results proved that the 3D-printing process was highly suitable for producing composite stents (approximately 85–95% accuracy). Both PCL and PLA demonstrated their biocompatibility with PCL stents presenting an average cell proliferation of 12.46% and PLA 8.28% after only 3 days. Furthermore, the PCL/PLA composite stents demonstrated their potential in degradation, dynamic mechanical and expansion tests. Moreover, and regardless of the order of the layers, the composite stents showed (virtually) medium levels of degradation rates and mechanical modulus. Radially, they exhibited the virtues of PCL in the expansion step (elasticity) and those of PLA in the recoil step (rigidity). Results have clearly demonstrated that composite PCL/PLA stents are a highly promising solution to fulfilling the rigorous BRS requirements.

A Family of Highly Fluorescent and Unsymmetric Bis(BF2) Chromophore Containing Both Pyrrole and N-Heteroarene Derivatives: BOPPY.

A fundamental, highly fluorescent, and easily accessible scaffold named BOPPY is reported. The use of hydrazine as a bridging linkage between pyrrole and N-heteroarenes enables the binding of two BF2 units to provide sufficient rigidity of the unsymmetric core skeleton. These resultant unsymmetrical BOPPYs are thus highly fluorescent in their solutions and solid powder states and exhibit high molar absorption coefficients (42200-47000 M-1 cm-1), large Stokes shifts, excellent photostability, and insensitivity to pH. More importantly, these BOPPYs showed efficient two-photon absorption in the wide spectral range of 700-900 nm, making them well suited for two-photon fluorescence microscopy imaging in living cells.