Pressure drop across micro-pin heat sinks under boiling conditions

Two-phase pressure drop was studied in four different micro pin fin heat sinks. Micro pin fin heat sinks used in the current studies were operated under boiling conditions using water and R-123 as working fluids. It was observed that once boiling was initiated severe temperature fluctuations and flow oscillations were recorded for three of the micro pin fin heat sinks, which was characterized as unstable boiling. Pressure drop signals were presented just before and after the unstable boiling conditions. Flow images and FFT (fast Fourier Transform) profiles of pressure signals were used to explain experimental results and unstable nature in flow boiling observed in the three of the devices. Stable boiling conditions where the temperature and pressure drop had a steady and stable profile could be only obtained from one micro pin fin heat sink at high mass velocities. The two-phase pressure drop in this hydrofoil-based micro pin fin heat sink has been investigated using R-123 as the working fluid. Two-phase frictional multipliers have been obtained over mass fluxes from 976 to 2349 kg/m2. It has been found that the two-phase frictional multiplier is strongly dependent on flow pattern. The theoretical prediction using Martinelli parameter based on the laminar fluid and laminar gas flow represented the experimental data fairly well for the spray-annular flow. For the bubbly and wavy-intermittent flow, however, large deviations from the experimental data were recorded. The Martinelli parameter was used successfully to determine the flow patterns, which were bubbly, wavy-intermittent, and spray-annular flow in the current study

The inventory of problems-29 is a cross‑culturally valid symptom validity test: Initial validation in a Turkish community sample

Because the actuarial evidence base for symptom validity tests (SVTs) is developed in a specific population, it is unclear whether their clinical utility is transferable to a population with different demographic characteristics. To address this, we report here the validation study of a recently developed free-standing SVT, the Inventory of Problems-29 (IOP-29), in a Turkish community sample. We employed a mixed design with a simulation paradigm: The Turkish IOP–29 was presented to the same participants (N = 125; 53.6% female; age range: 19–53) three times in an online format, with instructions to respond honestly (HON), randomly (RND), and attempt to feign a psychiatric disorder (SIM) based on different vignettes. In the SIM condition, participants were presented with one of three scripts instructing them to feign either schizophrenia (SIM-SCZ), depression (SIM-DEP), or posttraumatic stress disorder (SIM-PTSD). As predicted, the Turkish IOP–29 is effective in discriminating between credible and noncredible presentations and equally sensitive to feigning of different psychiatric disorders: The standard cutoff (FDS ≥ .50) is uniformly sensitive (90.2% to 92.9%) and yields a specificity of 88%. Random responding produces FDS scores more similar to those of noncredible presentations, and the random responding score (RRS) has incremental validity in distinguishing random responding from feigned and honest responding. Our findings reveal that the classification accuracy of the IOP–29 is stable across administration languages, feigned clinical constructs, and geographic regions. Validation of the Turkish IOP–29 will be a valuable addition to the limited availability of SVTs in Turkish. We discuss limitations and future directions

İlk hendese

Hendeseye Yeni Başlayan Etfale Mahsus Olup Maarif Nezaret-İ Celilesi'nin En Son Müfredat Programına Tevfıken Tahrir Edilmişdir. Ön Ve Arka Cildler Bezemelidir. Eserde "İstanbul Eğitim Enstitüsü Kitaplığı" Ve "Darülmuallimîn Kütübhanesi" Mühürleri Vardır

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