Mitigation of wind-induced vibration of a tall residential building using liquid column vibration absorber

The most important thing in applying mass type dampers including Liquid Column Vibration Absorber (LCVA) is tuning its natural frequency to an optimum value which is a function of the natural frequency of the building and the mass ratio of damper to the building. However, exact prediction of the natural frequency of the building at design stage is very difficult especially for concrete buildings. Thus, continuous updating of the target frequency and correction of the design of the damper based on field measurement is necessary. In this paper, application of LCVAs to mitigate the wind-induced vibration of 64-story residential buildings is presented. The LCVA were designed to have adjustable dimension for vertical column to take the advantage of ease tuning and wide frequency range. For updating of initial design, the tuning and performance assessment of LCVA several tests and measurement were carried out. The ambient vibration measurement of a partially completed building and a completed building without water in LCVA was performed and final values of the width of vertical column and the height of water were determined from the system identification results based on the collected acceleration data. In addition, ambient vibration measurement of buildings with LCVA water was performed and the system identification results indicated that the apparent damping ratio due to LCVA was increased about 3.13 to 3.89 times

Innovative Wireless Power Receiver for Inductive Coupling and Magnetic Resonance Applications

This chapter presents a wireless power receiver for inductive coupling and magnetic resonance applications. The active rectifier with shared delay-locked loop (DLL) is proposed to achieve the high efficiency for different operation frequencies. In the DC–DC converter, the phase-locked loop is adopted for the constant switching frequency in the process, voltage, and temperature variation to solve the efficiency reduction problem, which results in the heat problem. An automatic mode switching between pulse width modulation and pulse frequency modulation is also adopted for the high efficiency over the wide output power. This chip is implemented using 0.18 μm BCD technology with an active area of 5.0 mm × 3.5 mm. The maximum efficiency of the active rectifier is 92%, and the maximum efficiency of the DC–DC converter is 92% when the load current is 700 mA

Estimating Net Benefits of Reallocation: Discrete Choice Models of Sport and Commercial Fishing

Increasing conflicts over allocation have heightened interest among fishery managers in reliable and comparable measures of the relative economic contribution of commercial and sport fisheries. This paper shows how discrete choice methods may be applied to develop comparable estimates of net economic benefits of a proposal to reallocate sockeye salmon from the commercial to the sport fishery in Alaska's Kenai River. The study estimates net benefits that include both market and nonmarket use values for three groups of fishers: sport anglers, commercial drift and setnet operators, and their crew members. Results for a midrange scenario for run size and price suggest that the commercial losses roughly offset sport gains. However, the particulars of this fishery are key to this result. The principal advantages of the discrete choice method are the flexibility of a micro decision model and comparable treatment of time and intangibles across different user groups. The principal disadvantages are increased data requirements and the difficulty of estimating confidence intervals.Ye

Mitigation of wind-induced vibration of a tall residential building using liquid column vibration absorber

The most important thing in applying mass type dampers including Liquid Column Vibration Absorber (LCVA) is tuning its natural frequency to an optimum value which is a function of the natural frequency of the building and the mass ratio of damper to the building. However, exact prediction of the natural frequency of the building at design stage is very difficult especially for concrete buildings. Thus, continuous updating of the target frequency and correction of the design of the damper based on field measurement is necessary. In this paper, application of LCVAs to mitigate the wind-induced vibration of 64-story residential buildings is presented. The LCVA were designed to have adjustable dimension for vertical column to take the advantage of ease tuning and wide frequency range. For updating of initial design, the tuning and performance assessment of LCVA several tests and measurement were carried out. The ambient vibration measurement of a partially completed building and a completed building without water in LCVA was performed and final values of the width of vertical column and the height of water were determined from the system identification results based on the collected acceleration data. In addition, ambient vibration measurement of buildings with LCVA water was performed and the system identification results indicated that the apparent damping ratio due to LCVA was increased about 3.13 to 3.89 times

Finite element modeling and experimental verification of lightweight steel floor vibration

Due to the lack of design standard and the difficulty of analysis, the floor vibration analysis of lightweight steel floors has received less attention than the analysis of typical floor structures. In this paper, the finite element model for lightweight steel floors is presented utilizing the rigid link and realistic support restraints. The rigid rink is used to solve the problem of difference in the centroid of beam, joist, and flooring material and to guarantee the same behavior of those members. Two different support restraints, all fixed restraint and mixture of fixed and released restraint, are used in the analysis. The finite element model is verified through the human impact loading test of the full-scale light-weight steel floors that have different joist condition and middle beam. The finite element analysis results indicate that the different joists having same moment of inertia yield similar natural frequencies, while the test results of full-scale floors show that the floor with the closed shaped joists yields higher natural frequency than the floor with open shaped joists. The test results also indicate that the finite element analysis using the mixture of fixed and released support restraint yields closer natural frequencies to those of actual floors

Management Trend for Unstable Pelvic Bone Fractures in Regional Trauma Centers: Multi-Institutional Study in the Republic of Korea

Purpose In the Republic of Korea, the use of trauma centers was recently adopted and is expected to have better outcome for severely injured patients. This study aimed to evaluate the clinical outcomes and treatment methods for unstable pelvic bone fractures in trauma centers. Methods The annual number of patients, clinical outcomes, and treatment methods of unstable pelvic bone fractures in three trauma centers from 2016 to 2020 were retrospectively reviewed. The patients were dichotomized into survivors and deceased, and demographic data, treatment, and clinical outcomes were compared. Multivariable analysis was performed to identify the factors associated with survival. Results Among 237 patients, 101 (42.6%) were deceased. Mortality was lower in the later period (2019–2020) compared with the early period (2016–2018; 33.6% vs. 50.0%, p = 0.011). Direct admission of an increasing number of patients to trauma centers reduced prehospital time. Although the use of angioembolization in treating pelvic bone fracture (p < 0.001), and the use of other treatment methods did not change significantly (2016–2020). Lower age, lowest systolic blood pressure in the trauma bay, and higher lactate level, international normalized ratio, the amount of packed red blood cell transfusion at 24 hours were positively associated with mortality in the multivariate analysis. Conclusion Increasingly more patients with unstable pelvic bone fracture were admitted to trauma centers; mortality improved. Angioembolization increased significantly and multi-disciplinary modality for early bleeding control was still essential

Determination of Risk Factors for Predicting Bladder-Urethra Injury in Cases of Pelvic Bone Fracture: A Retrospective Single Center Study

Purpose Pelvis fractures are associated with bladder and urethral injury (BUI). The purpose of this study was to identify risk factors associated with BUI in patients with pelvic fracture. Methods Patients (> 18 years) with pelvic injury (N = 314) at our hospital between January 2015 and June 2020 were retrospectively analyzed for age, sex, cause of injury, initial vital signs, urine red blood cell (RBC) count, Glasgow Coma Scale and Abbreviated Injury Scale score, Injury Severity Score, preperitoneal pelvic packing, and femur, lumbar spine, and pelvic fractures. Results Compared with the BUI-absent group, the BUI-present group had a greater percentage of patients who were male (79.2% vs. 55.9%; p = 0.026), had a urine RBC count/high power field (HPF) ≥ 30 (94.4% vs. 38.8%; p < 0.001), underwent preperitoneal pelvic packing (37.5% vs. 18.6%; p = 0.035), had symphysis pubis diastasis (33.3% vs. 11.7%; p = 0.008), and had sacroiliac joint dislocation (54.2% vs. 23.4%; p = 0.001). Independent risk factors associated with BUI were symphysis pubis diastasis [odds ratio (OR) was 3.958 (95% confidence interval: 1.191–13.154); p = 0.025] and a urine RBC count/HPF ≥ 30 [OR = 25.415 (95% confidence interval: 3.252–198.637); p = 0.006]. Of those with BUI, 15 patients were diagnosed at the trauma bay, and 9 had a delayed diagnosis. Conclusion Patients with pelvic injury who display symphysis pubis diastasis or have a urine RBC count/HPF ≥ 30 are at higher risk of BUI, therefore, further BUI investigations should be considered

Determination of risk factors associated with surgical site infection in patients undergoing preperitoneal pelvic packing for unstable pelvic fracture

Background Several recent studies have shown that preperitoneal pelvic packing (PPP) effectively produces hemostasis in patients with unstable pelvic fractures. However, few studies have examined the rate of surgical site infections (SSIs) in patients undergoing PPP following an unstable pelvic fracture. The purpose of the present study was to evaluate factors associated with SSI in such patients. Methods We retrospectively reviewed the medical charts of 188 patients who developed hemorrhagic shock due to pelvic fracture between April 2012 and May 2021. Forty-four patients were enrolled in this study. Results SSI occurred in 15 of 44 patients (34.1%). The SSIs occurred more frequently in cases of repacking during the second-look surgery (0 vs. 4 [26.7%], P=0.010) and combined bladder-urethra injury (1 [3.4%] vs. 4 [26.7%], P=0.039). The incidence of SSIs was not significantly different between patients undergoing depacking within or after 48 hours (12 [41.4%] vs. 5 [33.3%], P=0.603). The mean time to diagnosis of SSI was 8.1±3.9 days from PPP. The most isolated organism was Staphylococcus epidermidis. Conclusions Repacking and combined bladder-urethra injury are potential risk factors for SSI in patients with unstable pelvic fracture. Close observation is recommended for up to 8 days in patients with these risk factors. Further, 48 hours after PPP, removing the packed gauze on cessation of bleeding and not performing repacking can help prevent SSI. Additional analyses are necessary with a larger number of patients with the potential risk factors identified in this study