Structural control strategies for earthquake response reduction of buildings

Destructive seismic events continue to demonstrate the importance of mitigating these hazards to building structures. Structural control has been considered one of the most effective strategies to protect buildings from extreme dynamic events such as earthquakes and strong winds, and has been applied to numerous real buildings in recent years. Structural control strategies can be divided into four categories: passive, active, semi-active, and hybrid control. Because passive control systems are well understood and require no external power source, they have been accepted widely by the engineering community. However, these passive systems have the limitation of not being able to adapt to structural changes and to varying usage patterns and loading conditions. While active systems are able to adapt various conditions, they require a significant amount of power to generate the necessary large control forces; guaranteeing the availability of such power during seismic events is challenging. Moreover, the stability of active systems is not ensured. To compensate for the drawbacks of passive and active systems, semi active control systems have been proposed. Semi-active control devices possess the adaptability to flexible external inputs, do not require large power sources, and do not have the potential to destabilize the structural system. However, semi-active control has been slow to be accepted by engineering practitioners. The focus of this dissertation is the improvement and the validation of semi-active control strategies, especially with magnetorheological (MR) dampers, for building protection from severe earthquakes. To make semi-active control strategies more practical, further studies on both the numerical and experimental aspects of the problem are conducted. In the numerical studies, new algorithms for semi-active control are proposed. First, the nature of control forces produced by active control systems is investigated. The relationship between force-displacement hysteresis loops produced by the linear quadratic regulator (LQR) and the linear quadratic Gaussian (LQG) algorithms is explored. Then, new simple algorithms are proposed, which can produce versatile hysteresis loops. Moreover, the proposed algorithms do not require a model of the target structure to be implemented, which is a significant advantage. The seismic performance of the proposed algorithms on a scaled three-story building model is compared with the LQG-based clipped-optimal semi active control and LQG active control cases. In the experimental studies, the effectiveness of semi-active control strategies are shown through real-time hybrid simulation (RTHS) in which a MR damper is tested physically. In this dissertation, two new structural control methods proposed in the literature recently are investigated, i.e., smart outrigger damping systems for high-rise buildings and smart base isolation systems consisting of passive base isolations and semi-active control devices. The accuracy of the RTHS employing the model-based compensator for MDOF structures with a semi-active device is discussed as well. The research presented in this dissertation contributes the improvement and prevalence of semi-active control strategies in building structures to mitigate seismic damage

Outrigger tuned inertial mass electromagnetic transducers for high-rise buildings subject to long period earthquakes

This paper proposes outrigger tuned inertial mass electromagnetic transducer (TIMET) systems for high-rise buildings subject to long period earthquake excitations. The proposed outrigger TIMET systems consist of the outrigger and TIMET parts. The outrigger damping systems have been proposed as a novel energy dissipation approach to high-rise buildings, in which control devices are installed vertically between the outrigger and perimeter columns to achieve large energy dissipation. While the TIMET has been developed based on the mechanism of the tuned viscous mass damper (TVMD) which can improve energy absorbing capability by taking advantage of resonance effect. However, instead of a viscous material, the damping of the TIMET is provided by a motor which can convert mechanical energy to electrical energy. The focus of this study is to investigate the structural control performance and energy harvesting efficiency of the proposed outrigger TIMET system for high-rise buildings subjected to long period earthquakes through numerical simulations

Structural Control Strategies for Earthquake Response Reduction of Buildings

Destructive seismic events continue to demonstrate the importance of mitigating these hazards to building structures. To protect buildings from such extreme dynamic events, structural control has been considered one of the most effective strategies. Structural control strategies can be divided into four classes: passive, active, semi-active, and hybrid control. Because passive control systems are well understood and require no external power source, they have been accepted widely by the engineering community. However, these passive systems have the limitation of not being able to adapt to varying conditions. While active systems are able to do that, they require a significant amount of power to generate large control forces. Moreover, the stability of active systems is not ensured. The focus of this report is the improvement and the validation of semi-active control strategies, especially with MR dampers, for building protection from severe earthquakes. To make semi active control strategies more practical, further studies on both the numerical and experimental aspects of the problem are conducted. The research presented in this report contributes the improvement and prevalence of semi-active control strategies in building structures to mitigate seismic damage.Financial support for this research was provided in part by the Long Term Fellowship for Study Abroad by the MEXT (Ministry of Education, Culture, Sports, Science, and Technology, Japan) and the Newmark Account.Ope

Experimental characterization and performance improvement evaluation of an electromagnetic transducer utilizing a tuned inerter

This research reports on the experimental verification of an enhanced energy conversion device utilizing a tuned inerter called a tuned inertial mass electromagnetic transducer (TIMET). The TIMET consists of a motor, a rotational mass, and a tuning spring. The motor and the rotational mass are connected to a ball screw and the tuning spring interfaced to the ball screw is connected to the vibrating structure. Thus, vibration energy of the structure is absorbed as electrical energy by the motor. Moreover, the amplified inertial mass can be realized by rotating relatively small physical masses. Therefore, by designing the tuning spring stiffness and the inertial mass appropriately, the motor can rotate more effectively due to the resonance effect, leading to more effective energy generation. The authors designed a prototype of the TIMET and conducted tests to validate the effectiveness of the tuned inerter for electromagnetic transducers. Through excitation tests, the property of the hysteresis loops produced by the TIMET is investigated. Then a reliable analytical model is developed employing a curve fitting technique to simulate the behavior of the TIMET and to assess the power generation accurately. In addition, numerical simulation studies on a structure subjected to a seismic loading employing the developed model are conducted to show the advantages of the TIMET over a traditional electromagnetic transducer in both vibration suppression capability and energy harvesting efficiency

Energy harvesting potential of tuned inertial mass electromagnetic transducers

The demand for developing renewable energy technologies has been growing in today\u27s society. As one of promising renewable energy sources, large-scale energy harvesting from structural vibrations employing electromagnetic transducers has recently been proposed and considerable effort has been devoted to increase the power generation capability. In this paper, we introduce the mechanism of a tuned inertial mass electromagnetic transducer (TIMET), which can absorb vibratory energy more efficiently by tuning the parameters to adjust the system. Then we propose a new vibratory energy harvester with the TIMET and determine the parameter values for the device with a simple static admittance (SA) control law to maximize the energy harvested from a stationary stochastic disturbance. To investigate the energy harvesting potential of the TIMET further, the performance-guaranteed (PG) control and the LQG control proposed in the literature are applied as well. Then the numerical simulation studies are carried out and the effectiveness of the proposed energy harvester is examined by comparing the traditional electromagnetic transducers

Adjustable vertical vibration isolator with a variable ellipse curve mechanism

This paper presents a passive vertical quasi-zero-stiffness vibration isolator intended for relatively small objects. The present isolator has features of compactness, long stroke, and adjustability to various load capabilities. To realize these features, we use constant-force springs, which sustain constant load regardless of their elongation, and propose a variable ellipse curve mechanism that is inspired by the principle of ellipsographs. The variable ellipse curve mechanism can convert the restoring force of the horizontally placed constant-force springs to the vertical restoring force of the vibration isolator. At the same time as converting the direction, the vertical restoring force can be adjusted by changing the ratio of the semi-minor axis to the semi-major one of the ellipse. In this study, a prototype of a class of quasi-zero-stiffness vibration isolator with the proposed variable ellipse curve mechanism is created. Shaking table tests are performed to demonstrate the efficacy of the present mechanism, where the prototype is subjected to various sinusoidal and earthquake ground motions. It is demonstrated through the shaking table tests that the prototype can reduce the response acceleration within the same specified tolerance even when the mass of the vibration isolated object is change

The usefulness of a new gait symmetry parameter derived from Lissajous figures of tri-axial acceleration signals of the trunk

textabstractThis cross-country study adopts a competing theories approach in which both a value perspective and a social capital perspective are used to understand the relation between religion and a country’s business ownership rate. We distinguish among four dimensions of religion: belonging to a religious denomination, believing certain religious propositions, bonding to religious practices, and behaving in a religious manner. An empirical analysis of data from 30 OECD countries with multiple data points per country covering the period 1984–2010 suggests a positive relationship between religion and business ownership based on those dimensions that reflect the internal aspects of religiosity (i.e., believing and behaving). We do not observe a significant association for those dimensions that reflect more external aspects of religion (i.e., belonging and bonding). These results suggest that the social capital perspective prevails the value perspective, at least when internal aspects of religiosity are concerned. More generally, our study demonstrates the importance of distinguishing between different dimensions of religion when investigating the link between religion and entrepreneurship

ケンジョウジン ニオケル GAZE STABILITY EXERCISE ノ コウカ ジュウシン ドウヨウ ト ドウタイ シリョク デノ ケントウ

INTRODUCTION AND METHODS: The purpose of this study was to investigate the effectiveness of gaze stability exercises on healthy young subjects. Subjects were randomly divided into experimental （n=28） and control groups （n=13）. The experimental group performed gaze stability exercise for three weeks and the control group did not. Pre and post body sway during quiet standing, standing with neck rotation, and dynamic visual acuity were measured on both groups. RESULTS: The results showed significant differences in body sway during standing with neck rotation and dynamic visual acuity in the experimental group （p<0.01. No significant differences were found in body sway and dynamic visual acuity in the control group.） DISCUSSION AND CONCLUSION: These improvements in postural stability and dynamic visual acuity after three weeks of gaze stability exercises suggest improved neural adaptation of the vestibular nuclear complex and cerebellum, as well as enhanced central pre-programming. These results of this study suggest that gaze stability exercises may be beneficial for healthy young adults, and these data may be adapted to elderly or sports fields in further study

ミ チリョウ ゾウショク トウニョウビョウ モウマクショウ ニ タイスル ガラス タイ シュジュツ ノ チョウキ セイセキ : ガンカ チリョウ レイ トノ ヒカク

未治療増殖糖尿病網膜症に対する硝子体手術施行例の長期手術成績について検討した.対象は眼科未治療群19例24眼(初診時PC 未施行)で初回硝子体手術を施行し,術後3年以上経過観察できた症例とし,同期間内に初回硝子体手術を施行した眼科治療群(PC施行)30例31眼(control群)と比較検討した.内科未治療は眼科未治療群で52.6 %,control群では0%であった.初回手術時の病態では眼科未治療群で牽引性網膜剥離群(50.0%),control群で硝子体出血群(51.6%)が各群で最も多かった.術後合併症,再手術の原因は両群とも硝子体出血が最も多く認められた.術後最終視力は眼科未治療群で2段階以上の悪化例,0.1未満の視力不良例がcontrol群に比べて多く認められた.眼科未治療群はcontrol群に比べて視力予後不良のことが多いため,内科と眼科の連携を高め,早期のPCが必要であると考えられた.We evaluated long-term results of vitrectomy for untreatedproliferative diabetic retinopathy.We objected for 24 eyes of 19 patients who were untreatedgroup without PC and were underwent first-time vitrectomy,we compared with 30 eyes of 31 patients( controlledgroup)who were treated group(with PC)and were underwentfirst-time vitrectomy.54.2 % of the treated group and 0 % of the controlledgroup were treated by physician. In the status of first-timevitrectomy, traction retinal detachment group (50.0 %) inthe untreated group and vitreous hemorrhage group (51.6%) in the controlled group were the most of each group.Complications after vitrectomy and cause of reoperationshowed the most vitreous hemorrhage. In final visual acuityafter vitrectomy, it showed that untreated group was muchmore deteriorated 2 or more lines and showed 0.1 or lessthan controlled group.Untreated group was poor visual prognosis comparedwith controlled group. So we need to keep in contact withphysician and undergo PC as soon as possible

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target