Field Test for a Base Isolation Structure on Condition of Horizontal and Initial Displacement

There are a few isolated structures that have been subjected to seismic testing. An isolated structure is incapable of tracking, adjusting, and controlling its dynamic characteristics. As a result, field evaluations of solitary structures’ dynamic characteristics are important. The horizontal initial displacement of a base isolation kindergarten made of 46 isolation bearings is 75 mm. The method for creating the horizontal initial displacement condition is illustrated, as are the primary test findings. Horizontal initial displacement is accomplished with the assistance of a reaction wall, rods, and hydraulic pump system. To begin, we removed the building using hydraulic jacks to produce horizontal displacement of the isolation layer and then attached rods to support the building. The rods were then shot and unloaded, causing the building to shake freely, and its dynamic response and other parameters were tested. The results indicate that the natural vibration period of an isolated structure is much greater than the natural vibration period of a seismic structure. The isolation layer’s hysteretic curve as completely filled; upon unloading, the isolation layer as promptly reset; the dynamic response control effect of each was visible, but the top floor’s acceleration was magnified by approximately 1.27 times.

Molecular dynamics study on single particle displacement damage of ZB InN

To evaluate single-particle initial displacement damage of InN, the MD method is used to simulate the cascades, where the energy of PKA (E PKA) ranges from 1 to 5 keV. From these results, we can find that high EPKA will increase Np and Ns of defects, and aggravate the damage of InN, which is more obvious in Frenkel pairs. The formation efficiency of vacancy and interstitial is influenced by antisite defects, thereby causing the difference between vacancies and interstitials for the same atomic type. About the distribution of InN defects, it is mainly caused by vacancy defects, indicating that vacancy damage occupies the main position in displacement damage.

Influence of the initial winding displacement on the indicators of the electromechanical induction accelerator of cylindrical configuration

Purpose. The purpose of the article is to determine the influence of the initial displacement of the windings on the indicators of an electromechanical induction accelerator of a cylindrical configuration with pulsed excitation from a capacitive energy storage and with short-term excitation from an alternating voltage source. Methodology. To take into account the interrelated electrical, magnetic, mechanical and thermal processes, as well as a number of nonlinear dependencies, we use the lumped parameters of the windings, and the solutions of the equations describing these processes are presented in a recurrent form. The mathematical model of the accelerator takes into account the variable magnetic coupling between the windings during the excitation of the inductor winding. When calculating the parameters and characteristics of the accelerator, a cyclic algorithm is used. Results. At a frequency of an alternating voltage source of 50 Hz, the current amplitude in the armature winding is less than in the inductor winding. With an increase in the source frequency to 250 Hz, the phase shift between the winding currents decreases. The current in the inductor winding decreases, and in the armature winding it increases. The accelerating components of the force increase, and the braking ones decrease. With an increase in the source frequency to 500 Hz, the current density in the armature winding exceeds that in the inductor winding. In this case, the phase shift between the windings is further reduced. Originality. When a cylindrical accelerator is excited, the largest amplitude of the current density in the inductor winding occurs at the maximum initial displacement of the windings, but the amplitude of the current density in the armature winding is the smallest. The largest value of the current density in the armature winding occurs in the absence of an initial displacement. When excited from a capacitive energy storage, the electrodynamic force between the windings has an initial accelerating and subsequent braking components. As a result, the speed of the armature initially increases to a maximum value, but decreases towards the end of the electromagnetic process. When a cylindrical accelerator is excited from an alternating voltage source, a phase shift occurs between the currents in the windings, which leads to the appearance of alternating accelerating and decelerating components of electrodynamic forces. The accelerating components of the force prevail over the braking components, which ensures the movement of the armature. Practical value. At a frequency of an alternating voltage source of 50 Hz, the highest speed at the output of the accelerator vzf=0.5 m/s is realized at an initial displacement of the windings z0=6.2 mm, at a frequency of 250 Hz, the highest speed vzf=2.4 m/s is realized at z0=3.1 mm, and at a frequency of 500 Hz the highest speed vzf=2.29 m/s is realized at z0=2.3 mm.

Flux-mediated dark matter

We propose a new mechanism to communicate between fermion dark matter and the Standard Model (SM) only through the four-form flux. The four-form couplings are responsible for the relaxation of the Higgs mass to the correct value and the initial displacement of the reheating pseudo-scalar field from the minimum. We show that the simultaneous presence of the pseudo-scalar coupling to fermion dark matter and the flux-induced Higgs mixing gives rise to unsuppressed annihilations of dark matter into the SM particles at present, whereas the direct detection bounds from XENON1T can be avoided. We suggest exploring the interesting bulk parameter space of the model for which dark matter annihilates dominantly into a pair of singlet-like scalars with similar mass as for dark matter.

The non-stationary delay of establishment nonlinear vibrations in the system of two connected oscillators. Part 3. Determinating equation.

This work is the continuation of investigation of non-stationary delay of establishment nonlinear vibrations in the system of two connected oscillators. The physical foundation of this task is the excitation of power hypersound in ferrite plate having magnetoelastic properties and also excitation of intensive electromagnetic vibrations in ferrite disc placed in electro-dynamic resonator. The foundation of this work is received in the first part of this work the simplified system of two connected differential second order equations having vibration character. As a main step of simplification of the task it is made the substitution of the vibration of second oscillator by auxiliary function having harmonic dependency from the time. In this case the dynamic potential acquired the character of periodic “jumps” in forward and backward directions. By this circumstance the introduced function was named as “jumping”. As a result of introduction of jumping function it was the replacement of two equations of initial system by only one “determination” equation which maintains the properties of the large-amplitude chaos and non-stationary delay. On the basis of determination equation it is investigated the development of vibrations and founded its derivative in the time and the parametrical portrait is constructed. It is shown that the development of vibrations feels large delay in time which value surpass the period of jumping function about some times. When the delay is over it is developed by the sudden jump the non-stationary vibrations having the amplitude which surpass the initial displacement more then three orders. The parametrical portrait has the form of horizontal eight which is typical for chaotic vibrations. The spectrum composition of large-amplitude chaos is investigated. It is shown that in the whole spectrum is predominated the line which is correspond to frequency of jumping function. When this function is removed it is remained only clean chaos. The width of spectrum of this chaos exceeds the frequency of jumping function on two orders. The influence of initial displacement on delay time is investigated. It is shown that the delay time is depended on the value of initial displacement in the frame of inverse proportion law. The influence of jumping function amplitude on the delay time is investigated. It is found the critical value of this amplitude. It is shown that in the lower level of critical value the large-amplitude chaos is absent. It is shown that when the amplitude of jumping function increases the delay time is decreases. But on the general smooth dependence it is displaced some sharp maxima which correspond to sharp increasing of delay time on the value about one order and more. As a possible explanation of this dependence character it is proposed the hypothesis about its resonance character. The influence of jumping function frequency on the delay time is investigated. It is shown that when this frequency is increased the delay time also increases right until its critical value. Above the level of critical value the large-amplitude chaos is absent. It is noted the analogy of this phenomenon with the excitation of electric vibration circuit by sinusoidal force. In this case on the low frequency the current in the circuit vibrates in the same phase with excitation force and after the overcoming the resonance frequency the vibrations becomes in opposite phase. On the received dependence it if found some narrow maxima which corroborate the hypothesis about its resonance character. It is found that the determination equation contains inertial and potential parts for the characteristics of which is introduced the inertial and potential parameters as a coefficients by second derivative and item of cubic nonlinearity. The influence of inertial parameter on the delay time is investigated. It is found the critical value of this parameter lower of which the large-amplitude chaos is absent. The influence of potential parameter on the delay time is investigated. It is found that the excitation of large-amplitude chaos is possible along unlimited range of this parameter without some critical value. The influence of phase displacement of jumping function in comparison with initial moment of excitation on the delay time is investigated. It is found very strong dependence which is differed by small and large delay times. The small value of delay time is characterized by absence of sharp maxima on the dependence of delay time from initial displacement. It is shown that in this case the dependence of delay time from of phase displacement has very wide maximum when the dependence of jumping function is negative. In this region the large-amplitude chaos is absent. It is found that by large delay times so as in region of sharp maxima on the dependence of delay time from initial displacement the influence of phase displacement of jumping function is sharp increased. It is proposed some comments about possible development of this work. As a general tasks it is mentioned the construction of model idea about duration of delay time, more detailed clarification of nature of critical character of some parameters and more detailed investigation of phase character of described phenomena.

Open reduction and internal fixation for displaced Salter-Harris type II fractures of the distal tibia: a retrospective study of sixty-five cases in children

Background The treatment for displaced Salter-Harris II (S-H II) distal tibia fractures remains controversial. The purpose of this study was to review S-H II distal tibia fractures and evaluate the rate of premature physeal closure (PPC) treated by open reduction and internal fixation (ORIF). Methods We reviewed the charts and radiographs of S-H II fractures of the distal tibia with displacement > 3 mm between 2012 and 2019 treated by ORIF. Patients were followed up for a minimum of 6 months. CT scans of injured side or contralateral ankle radiograph were obtained if there was any evidence of PPC. Any angular deformity or shortening of the involved leg was documented. Multivariable logistic regression was performed to identify risk factors for the occurrence of PPC. Results A total of 65 patients with a mean age of 11.8 years were included in this study. The mean initial displacement was 8.0 mm. All patients but one were treated within 7 days after injury and the mean interval was 3.7 days. Supination-external rotation injuries occurred in 50 patients, pronation-eversion external rotation in 13, and supination-plantar flexion in two. The residual gap was less than 1 mm in all patients following ORIF and all fractures healed within 4–6 weeks. Superficial skin infection developed in one patient. Ten patients complained of the cosmetic scar. The rate of PPC was 29.2% and two patients with PPC developed a varus deformity of the ankle. Patients with associated fibular fracture had 7 times greater odds of developing PPC. Age, gender, injured side, mechanism of injury, amount of initial displacement, interval from injury to surgery, or energy of injury did not significantly affect the rate of PPC. Conclusions ORIF was an effective choice of treatment for S-H II distal tibia fractures with displacement > 3 mm to obtain a satisfactory reduction. PPC is a common complication following ORIF. The presence of concomitant fibula fracture was associated with PPC.

Open Reduction and Internal Fixation for Displaced Salter-Harris type II Fractures of the Distal Tibia: A Retrospective Study of Eighty-Five Cases in Children

Background: The treatment for displaced Salter-Harris Ⅱ distal tibia fractures remains controversial. The purpose of this study was to evaluate the rate of premature physeal closure (PPC) and to identify the risk factors treated by open reduction and internal fixation.Methods: We reviewed the charts and radiographs of patients with Salter-Harris Ⅱ fractures of the distal tibia with displacement >3mm between 2012 and 2019. Open reduction and internal fixation was performed for all patients. Patients were followed up for a minimum of 4 months. Contralateral ankle radiograph or CT scans were obtained if there was any evidence of premature physeal closure. Any angular deformity or shortening of the involved leg was documented.Results: A total of 85 patients with a mean age of 12.3years were included in the study. The mean initial displacement was 8.5 mm. All patients but one were treated within seven days after injury and the mean interval was 3.7 days. SER injuries occurred in 65 patients (76.5%), PER in 17 (20.0%), and SPF in three (3.5%). The rate of PPC was 29.4% and two patients with PPC had varus deformities. The rate of PPC was significantly greater in patients with associated fibular fracture as compared with those with intact fibular (P=0.005). Patient age, gender, injured side, mechanism of injury (only SER vs PER), amount of initial displacement, interval from injury to surgery, or energy of injury did not affect the rate of PPC significantly. Conclusions: PPC is a common complication for displaced S-H Ⅱ distal tibia physeal fractures. We suggest that open reduction internal fixation is an effective choice to reduce the risk of PPC. The presence of concomitant fibula fracture was associated with PPC.

Forced (im)mobilities en route: ‘Justified’ violence of the border regime in Balkans

In this article, I explore the violent consequences of the post-2015 EU border regime for people from the Global South lingering through the Balkans. I intend to show that securing EU?s external borders through asylum and border management in Balkans is based on coercion and force, despite the efforts of the people on the move to transgress these borders and achieve decent lives. The efforts of people on the move to cross borders - which are officially closed for them - could be understood as force as well. Regardless of the legal status and ?motives? of displacement, people waiting and moving on the ?Balkan route? experience situations characterized by structural, direct, and cultural violence and respond to these situations in different ways. Pointing out to more or less hidden patterns of violence occurring at the EU?s external borders in the Balkans may challenge popular categorizations that at the same time oppress and protect people on the move. These patterns of violence are justified - but not justifiable - by the securitization of EU and national borders. By displacing violence as the so-called ?push? factor from the countries of initial displacement (i.e. countries of the Global South), I aim to acknowledge that it continues to be perpetrated en route. Patterns of violence in the Balkans further produce forced mobilities and forced immobilities. People on the move cope with these forced (im)mobilities in different ways.