Semi-Active System of Vehicle Vibration Damping

This article discusses the vibration of a vehicle equipped with four semi-active dampers. The friction forces generated in these dampers have crucial influence on the intensity of the vehicle vibration. To estimate the effect of the vehicle vibration damping, a criterial function depending on the values of these forces has been selected. Solving the problem has the purpose of determining four values of the forces at which the criteria function reaches the minimum at any moment. On the basis of the above, signals for the devices controlling the operation of the semi-active dampers are determined. In this work, the analysis of the discussed problem was conducted in regard to the method for determining the optimal force values. Moreover, the results of the simulation of the vibration of the vehicle equipped with semi-active magneto-rheological dampers are presented. In addition, the analysis of the influence of the form of the criterial function on the vehicle vibration damping efficiency is proposed. Based on the tests carried out on the vehicle with MR dampers, the comfort index improved by 51.6%, compared to the classic suspension.

Regulatory Light Chains in Cardiac Development and Disease

The role of regulatory light chains (RLCs) in cardiac muscle function has been elucidated progressively over the past decade. The RLCs are among the earliest expressed markers during cardiogenesis and persist through adulthood. Failing hearts have shown reduced RLC phosphorylation levels and that restoring baseline levels of RLC phosphorylation is necessary for generating optimal force of muscle contraction. The signalling mechanisms triggering changes in RLC phosphorylation levels during disease progression remain elusive. Uncovering this information may provide insights for better management of heart failure patients. Given the cardiac chamber-specific expression of RLC isoforms, ventricular RLCs have facilitated the identification of mature ventricular cardiomyocytes, opening up possibilities of regenerative medicine. This review consolidates the standing of RLCs in cardiac development and disease and highlights knowledge gaps and potential therapeutic advancements in targeting RLCs.

Optimal destabilization of cartels

This paper introduces an oligopoly model that includes three actors: a cartel (comprising two or more firms that operate like one merged company), a group of competing fringe firms, and a welfare maximizing antitrust authority. The cartel is the Stackelberg quantity leader and the fringe firms are in Cournot competition with respect to the residual demand. The cartel is internally stable if none of its member firms finds it profitable to become a fringe firm. The antitrust authority can destabilize the cartel in the sense of making the cartel internally instable. To this end, the antitrust authority has three policy instruments at its disposal: its own effort, a fine for detected cartels, and a leniency program for cartel members that cooperate with the authority. Taking into account that the use of these instruments is not costless for society, a unique optimal antitrust policy is derived. The analysis reveals that both, the optimal force and mix of the antitrust authority’s policy depend on market characteristics such as the efficiency of the authority’s operations, the public respect for the rule of law, the ethical standards of the firms’ managers, the market volume, and the number of firms operating on the market.

Optimization of Underbody Blast Energy-Attenuating Seat Mechanisms Using Modified MADYMO Human Body Models

Though energy attenuating (EA) seats for air and spacecraft applications have existed for decades, they have not yet been fully characterized for their energy attenuation capability or resulting effect on occupant protection in vertical underbody blast. EA seats utilize stroking mechanisms to absorb energy and reduce the vertical forces imparted on the occupant's pelvis and lower spine. Using dynamic rigid-body modeling, a tool to determine optimal force and deflection limits was developed to reduce pelvis and lower spine injuries in underbody blast events using a generic seat model. MAthematical DYnamic MOdels (MADYMO) and modeFRONTIER software were leveraged for this study. This optimizing tool may be shared with EA seat manufacturers and applied to military seat development efforts for EA mechanisms for a given occupant and designated blast severity. To optimally tune the EA seat response, the MADYMO Human Body Model (HBM) was first updated to improve its fidelity in kinematic response data for high rate vertical accelerative loading relative to experimental data from laboratory simulated underbody blast tests using post-mortem human surrogates (PMHS). Subsequently, using available injury criteria for underbody blast, the optimization tool demonstrated the ability to identify successful EA mechanism configurations to reduce forces and accelerations in the pelvis and lower spine HBM to presumed non-injurious levels. This tool could be tailored by varying input pulses, force and deflection limits, and occupant size to evaluate EA mechanism designs.

An Assistive Soft Wrist Exosuit for Flexion Movements With an Ergonomic Reinforced Glove

Soft exosuits are a promising solution for the assistance and augmentation of human motor abilities in the industrial field, where the use of more symbiotic wearable robots can avoid excessive worker fatigue and improve the quality of the work. One of the challenges in the design of soft exosuits is the choice of the right amount of softness to balance load transfer, ergonomics, and weight. This article presents a cable-driven based soft wrist exosuit for flexion assistance with the use of an ergonomic reinforced glove. The flexible and highly compliant three-dimensional (3D)-printed plastic structure that is sewn on the glove allows an optimal force transfer from the remotely located motor to the wrist articulation and to preserve a high level of comfort for the user during assistance. The device is shown to reduce fatigue and the muscular effort required for holding and lifting loads in healthy subjects for weights up to 3 kg.

Designing of minimum mass airframes under several loadings

We discuss the features of optimal force transfer in a thin-walled structure and use them to develop a method for defining the distribution of material over the structure elements for minimizing its volume. The suggested method works with one or several external loadings and allows one to determine the optimal structure and to recognize the phenomenon of Razani in which a structure with unequal stresses due to several loadings is more light-weight than a fully- stressed one. Using the developed method, we solved the original Razani problem and applied it for the optimization of the wing structure of a novel hypersonic airplane. It is shown that the determined material distribution is 8.78% lighter than that in a conventionally fully-stressed structure.

FUNCTIONAL EVALUATION OF MASTICATORY MUSCLES DURING THE INCREASED PHYSICAL EXERTION

Subject. The dentist using electroneuromyography can determine the amplitude, nature of work and the degree of symmetry of the muscles in various conditions. Biopotentials of musculus masseter and musculus temporalis change during the exercise depending on the severity of physical activity, because they have a previously developed algorithm of muscle contraction. Aim is to analyze the degree of symmetry of the masticatory muscles depending on the chewing side preference Methodology. 26 people were examined in the investigation. They completed special questionnaire. The state of the masticatory muscles was determined by palpation, then the muscles were examined in various functional states using the electroneuromyograph. Results. When a participant have done an exercise (bench press with dumbbells), the lower jaw lost its mainstay. The optimal force of muscle closure was determined to restore the balance of the musculus masseter. Due to musculus temporalis contraction, the occlusal axis was changed more medially to the premolar and the lower jaw was pushed slightly forward. As a result, after finding a mainstay, the work of musculus masseter and musculus temporalis leveled off and became more synchronous in order to achieve the coordinated and balanced work of musculus masseter, musculus temporalis and also of the musculoskeletal system as a whole. Conclusions. Planning the treatment dentist should attend to restoration of the teeth tubercles on the chewing sides preference and non-preference, because the contraction of the musculus masseter and musculus temporalis on the right and on the left is not synchronous.

Analysis of the Force-Velocity Profile in Female Ballet Dancers

Jumping ability has been identified as one of the best predictors of dance performance. The latest findings in strength and conditioning research suggest that the relationship between force and velocity mechanical capabilities, known as the force-velocity profile, is a relevant parameter for the assessment of jumping ability. In addition, previous investigations have suggested the existence of an optimal force-velocity profile for each individual that maximizes jump performance. Given the abundance of ballistic actions in ballet (e.g., jumps and changes of direction), quantification of the mechanical variables of the force-velocity profile could be beneficial for dancers as a guide to specific training regimens that can result in improvement of either maximal force or velocity capabilities. The aim of this study was to compare the mechanical variables of the force-velocity profile during jumping in different company ranks of ballet dancers. Eighty-seven female professional ballet dancers (age: 18.94 ± 1.32 years; height: 164.41 ± 8.20 cm; weight: 56.3 ± 5.86 kg) showed high force deficits (> 40%) or low force deficits (10% to 40%) regardless of their company rank. Our results suggest that dance training mainly develops velocity capabilities, and due to the high number of dramatic elevations that dance performance requires, supplemental individualized force training may be beneficial for dancers. The individualization of training programs addressed to the direction of each individual's imbalance (high force or low force) could help dancers and their teachers to improve jump height and therefore dance performance.