A Proper Shape of the Trailing Edge Modification to Solve a Housing Damage Problem in a Gas Turbine Power Plant

To solve the housing damage problem of a fractured compressor blade (CB) caused by an impact on the inner casing of a gas turbine in the seventh stage (from 15 stages), modifications of the trailing edge (TE) of the CB have been proposed, namely 6.5 mm curved cutting and a combination of 4 mm straight cutting with 6.5 mm curved cutting. The simulation results of the modifications in both aerodynamics variables Cl and Cd and the pressure ratio, including structural dynamics such as a normalized power spectrum, frequency, total deformation, equivalent stress, and the safety factor, found that 6.5 mm curved cutting could deliver the aerodynamics and structural dynamics similar to the original CB. This result also overcomes the previous work that proposed 5.0 mm straight cutting. This work also indicates that the operation of a CB gives uneven pressure and temperature, which get higher in the TE area. The slightly modified CB can present the difference in the properties of both the aerodynamics and the structural dynamics. Therefore, any modifications of the TE should be investigated for both properties simultaneously. Finally, the results from this work can be very useful information for the modification of the CB in the housing damage problem of the other rotating types of machinery in a gas turbine power plant.

Associations Between Community Social Capital and Preservation of Functional Capacity in the Aftermath of a Major Disaster

The strength of social connections in the community (“social capital”) is hypothesized to be a crucial ingredient in disaster resilience. We examined whether community-level social capital is correlated with the ability to maintain functional capacity among older residents who experienced the 2011 Great East Japan Earthquake and Tsunami. The baseline of our cohort (mean age, 74 years) was established in 2010, 7 months before the disaster in Iwanuma, a Japanese city located 80 km from the epicenter. Disaster-related personal experiences (e.g., housing damage or relocation) were assessed through a follow-up survey (n = 3,594; follow-up rate, 82.1%) conducted in 2013, 2.5 years after the earthquake. Multiple membership multilevel models were used to evaluate the associations between functional capacity, measured by the Instrumental Activities of Daily Living scale, and 3 subscales of community-level social capital: social cohesion, social participation, and reciprocity. Community-level social participation was associated with a lower risk of functional decline after disaster exposure. The average level of social participation in the community also mitigated the adverse impact of housing damage on functional status, suggesting a buffering mechanism.

Investigation of the Trailing Edge Modification Effect on Compressor Blade Aerodynamics Using SST k-ω Turbulence Model

A gas turbine power plant in Thailand had the problem of compressor blade fracture in Stages 6–8, which was caused by housing damage. This gas turbine has a total of 15 stages. The housing damage reduced the lifetime of blades to an unacceptable level. This article shall report the solution and outcomes. Three-dimensional (3D) compressor blade models in the problematic stages were prepared by a 3D scanning machine to find a solution based on computational fluid dynamics (CFD), and then were completed for simulation by adding Stages 5 and 9 to become a multi-stage axial model. The latter models were modified by trimming the trailing edge by 1, 5-, and 10-mm. Using ANSYS CFX R19.2 software, the CFD results of the trailing edge modification effect on flow using the shear stress transport (SST) k-ω turbulence model revealed aerodynamics inside the problematic stages both before and after blade modifications. Modifying the blade by 5 mm was suitable, because it had lesser effects on aerodynamic parameters: pressure ratio, drag, and lift coefficients, when compared to the modification of 10 mm. The larger the modification, the greater the effect on aerodynamics. The effects on aerodynamics were intensified when they were modified by 10 mm. The validation of base line blades was conducted for the overall compressor parameters that were compared with the measurable data. These results were accepted and gave positive feedbacks from engineers who practically applied our reports in a real maintenance period of gas turbine.

Long-Term Associations Between Disaster Experiences and Cardiometabolic Risk: A Natural Experiment From the 2011 Great East Japan Earthquake and Tsunami

We investigated the association between disaster experience and the cardiometabolic risk of survivors 2.5 years after disaster onset, adjusting for health information predating the disaster, using natural experiment data stemming from the 2011 Great East Japan Earthquake and Tsunami. We used data from a cohort of adults aged 65 years or older in Iwanuma City, Japan, located 80 km (128 miles) west of the earthquake epicenter. The baseline survey was completed 7 months before the disaster, and the follow-up survey was performed among survivors approximately 2.5 years after the disaster. The survey data were linked to medical records with information on objectively measured cardiometabolic risk factors (n = 1,195). The exposure of interest was traumatic disaster experiences (i.e., housing damage and loss of loved ones). Fixed-effects regression showed that complete housing destruction was significantly associated with a 0.81-unit greater change in body mass index (weight (kg)/height (m)2; 95% confidence interval (CI): 0.24, 1.38), a 4.26-cm greater change in waist circumference (95% CI: 1.12, 7.41), and a 4.77-mg/dL lower change in high-density lipoprotein cholesterol level (95% CI: −7.96, −1.58) as compared with no housing damage. We also observed a significant association between major housing damage and decreased systolic blood pressure. Continued health checkups and supports for victims who lost homes should be considered to maintain their cardiometabolic health.

THOR (PENDETEKSI TANAH LONGSOR): DETEKSI BENCANA TANAH LONGSOR MENGGUNAKAN SENSOR “TASBIH” BERBASIS SMS GATEWAY

Indonesia has many landslide prone areas. During 2017, a total of 438 occurrences of landslides in Indonesia. Tragically there are many found settlements located on hillsides prone to landslides. It is evident that almost every year there is the occurrence of landslide natural disaster that cause casualties, at least is housing damage. This research to find a solution and other innovations by creating a device called THOR (Pendeteksi Tanah Longsor) wich the production cost is cheap and easy to operate. The procedure of this device is detecting every cracks in areas prone to landslides. If then there is cracks more than tolerable limit and indicated to be a landslide, the tasbih sensor will transmit warning by sirens and short message services for the local people. By those warning, the local people who stay in a prone landslide area will be alert and immediately evacuated. The test results of THOR are showing the functionality of all the components running well. The speed of the indicator light response to the sensor averaged 0.73 seconds. As for the speed of notification alarms sirine or buzzer averaged 0.79 seconds, and notification speed of sms broadcast from sms gateway has an average time lag of 143 seconds. Keywords: landslide, buzzer, sms gateway AbstrakIndonesia selama tahun 2017 ini, tercatat 438 kejadian bencana longsor di Indonesia. Tragisnya ternyata banyak didapati pemukiman yang berlokasi di lereng bukit yang rawan terjadi longsor. Penelitian ini bertujuan untuk mengembangkan sebuah alat yang bernama THOR (Pendeteksi Tanah Longsor) dengan biaya pembuatan yang murah serta mudah pengoperasiannya. Metode penelitian yang digunakan adalah Penelitian Pengembangan dengan pendekatan water fall. Cara kerja alat ini, yaitu mendeteksi setiap keretakan tanah pada daerah-daerah yang rawan longsor, jika terjadi keretakan tanah yang melebihi batas toleransi dan diindikasi menyebabkan longsor maka sensor tasbih akan mengirimkan peringatan melalui sirine dan juga sms untuk warga sekitar. Sehingga kemungkinan untuk terjadinya korban jiwa dapat diminimalisir. Hasil ujicoba alat THOR menunjukkan fungsionalitas dari semua komponen penyusun berjalan dengan baik. Kecepatan respon lampu indikator terhadap sensor rata-rata 0,73 detik. Sedangkan untuk kecepatan alarm pemberitahuan berupa sirine atau buzzer rata-rata 0,79 detik, dan kecepatan pemberitahuan berupa broadcast sms dari sms gateway ada jeda waktu rata-rata 143 detik. Kata Kunci : tanah longsor, buzzer, sms gateway