A suspended microchannel with integrated temperature sensors for high-pressure flow studies

A freestanding microchannel, with integrated temperature sensors, has been developed for high-pressure flow studies. These microchannels are approximately 20μm x 2μm x 4400μm, and are suspended above 80 μm deep cavities, bulk micromachined using BrF3 dry etch. The calibration of the lightly boron-doped thermistor-type sensors shows that the resistance sensitivity of these integrated sensors is parabolic with respect to temperature and linear with respect to pressure. Volumetric flow rates of N2 in the microchannel were measured at inlet pressures up to 578 psig. The discrepancy between the data and theory results from the flow acceleration in a channel, the non-parabolic velocity profile, and the bulging of the channel. Bulging effects were evaluated by using incompressible water flow measurements, which also measures 1.045x10^-3N-s/m^2 for the viscosity of DI water. The temperature data from sensors on the channel shows the heating of the channel due to the friction generated by the high-pressure flow inside

Notch effects in tensile behavior of AM60 magnesium alloys

The deformation and failure behavior of an AM60 magnesium alloy was investigated using tensile test on circumferentially notched specimens with different notch radii. The strain and stress triaxiality corresponding to the failure point were evaluated using both analytical and finite element analyses. Combining with systematical observations of the fracture surfaces, it is concluded that deformation and failure of AM60 magnesium alloy are notch (constraint) sensitive. The failure mechanisms change from ductile tearing to quasi cleavage with the increase of constraint

Micro heat exchanger by using MEMS impinging jets

A micro impinging-jet heat exchanger is presented here. Heat transfer is studied for single jet, slot arrays and jet arrays. In order to facilitate micro heat transfer measurements with these devices, a MEMS sensor chip, which has an 8 x 8 temperature-sensor array on one side, and an integrated heater on the other side has been designed and fabricated. This sensor chip allows 2-D surface temperature measurement with various jets impinging on it. It is found that micro impinging jets can be highly efficient when compared to existing macro impinging-jet microelectronics packages such as IBM 4381. For example, using a single nozzle jet (500-μm diameter driven by 5 psig pressure), the sensor chip (2 x 2 cm^2) temperature can be cooled down from 70 to 33°C. The cooling becomes more efficient when nozzle arrays (4x5 over 1 cm^2 area) are used under the same driving pressure. Interestingly, although higher driving pressure gives better cooling (lower surface temperature), the cooling efficiency, defined as h/0.5pv^2, is actually higher for lower driving pressure

Fungsi Kode dalam Program Acara “Beleter” Tvri Kalbar

Penelitian ini bertujuan untuk mendeskripsikan fungsi kode serta faktor yang melatarbelakangi pemilihan kode kebahasaan dalam program acara “Beleter” TVRI Kalbar. Metode yang digunakan dalam penelitian ini yaitu metode deskriptif dan bentuk penelitian kualitatif. Teknik dalam pengumpulan data ini yaitu wawancara, studi dokumentasi atau dokumen dan teknik simak, sedangkan alat pengumpul data dalam penelitian ini terdiri dari kartu pencatat data, tape recorder, dan lembar pedoman wawancara. Teknik analisa data menggunakan model Miles dan Huberman yaitu pertama, pengumpulan data, kedua, reduksi data, ketiga, penyajian data, dan keempat, penarikan simpulan. Hasil penelitian berdasarkan Fungsi kode yang terdapat pada penelitian yaitu terdapat lima fungsi, fungsi emotif, fungsi konatif, fungsi referensial, fungsi puitik dan fungsi fatik. Faktor yang melatarbelakangi pemilihan kode kebahasaan yaitu hal yang sudah direncanakan, pembicara atau penutur, pendengar atau lawan tutur dan Perubahan situasi karena hadirnya orang ketiga

Three essays on the time series of returns

This dissertation consists of three essays on the time series of asset returns. The first essay in Chapter 1--Time-Varying Drivers of Stock Prices--provides novel evidence of the time-varying roles of subjective expectations in explaining stock price variations across the market and 30 industry portfolios monthly from 1976 to 2020. Cash flow expectations matter more under financial uncertainty and recessions, especially among the hardest-hit industries such as Telecommunications during the Dot-com Bubble, Financials during the Great Recession, and Healthcare during the Covid-19 pandemic. Conversely, discount rates explain more price variations during expansionary periods. Finally, inflation expectations, while accounting for 60 percent of price fluctuations in the high inflationary environment before 2000, play a negligible role thereafter. In the second essay in Chapter 2--Investor Sentiment and Asset Returns: Actions Speak Louder than Words--I analyze daily predictability of investor sentiment across four major asset classes and compares sentiment measures based on news and social media with those based on trade information. For the majority of assets, trade-based sentiment measures outperform their text-based equivalents for both in-sample and out-of-sample predictions. This outperformance is particularly noticeable in long-term forecasts. However, real-time mean-variance investors can only achieve economic gains using Bitcoin trade sentiment, suggesting the challenge of transforming sentiment into daily profitable trading strategies. In the last essay in Chapter 3--War Discourse and Disaster Premia: 160 Years of Evidence from Stock and Bond Markets--using a semi-supervised topic model on 7,000,000 New York Times articles spanning 160 years, I test whether topics of media discourse predict future stock and bond market returns to test rational and behavioral hypotheses about market valuation of disaster risk. Focusing on media discourse addresses the challenge of sample size even when major disasters are rare. Our methodology avoids look-ahead bias and addresses semantic shifts. War discourse positively predicts market returns, with an out-of-sample R2 of 1.35 percent, and negatively predicts returns on short-term government and investment-grade corporate bonds. The predictive power of war discourse increases in more recent time periods.Includes bibliographical references

Experimental Study On Z-Pinned DCB Mode I Delamination

An experimental investigation on mode I delamination of z-pinned double-cantilever-beams (DCB) and corresponding pin pullout behaviour is presented. The effects of loading rate on delamination crack opening and z-pin bridging mechanisms is reported. Optical micrographs of z-pins after pullout show that a higher loading rate causes more splitting damage in the pins. Comparison of fracture load shows that the fracture load rises with increasing loading rate. Z-pin pullout tests were also conducted to give a detailed description of z-pin bridging mechanisms

Distinct roles of delta- and theta-band neural tracking for sharpening and predictive coding of multi-level speech features during spoken language processing

The brain tracks and encodes multi‐level speech features during spoken language processing. It is evident that this speech tracking is dominant at low frequencies (<8 Hz) including delta and theta bands. Recent research has demonstrated distinctions between delta‐ and theta‐band tracking but has not elucidated how they differentially encode speech across linguistic levels. Here, we hypothesised that delta‐band tracking encodes prediction errors (enhanced processing of unexpected features) while theta‐band tracking encodes neural sharpening (enhanced processing of expected features) when people perceive speech with different linguistic contents. EEG responses were recorded when normal‐hearing participants attended to continuous auditory stimuli that contained different phonological/morphological and semantic contents: (1) real‐words, (2) pseudo‐words and (3) time‐reversed speech. We employed multivariate temporal response functions to measure EEG reconstruction accuracies in response to acoustic (spectrogram), phonetic and phonemic features with the partialling procedure that singles out unique contributions of individual features. We found higher delta‐band accuracies for pseudo‐words than real‐words and time‐reversed speech, especially during encoding of phonetic features. Notably, individual time‐lag analyses showed that significantly higher accuracies for pseudo‐words than real‐words started at early processing stages for phonetic encoding (<100 ms post‐feature) and later stages for acoustic and phonemic encoding (>200 and 400 ms post‐feature, respectively). Theta‐band accuracies, on the other hand, were higher when stimuli had richer linguistic content (real‐words > pseudo‐words > time‐reversed speech). Such effects also started at early stages (<100 ms post‐feature) during encoding of all individual features or when all features were combined. We argue these results indicate that delta‐band tracking may play a role in predictive coding leading to greater tracking of pseudo‐words due to the presence of unexpected/unpredicted semantic information, while theta‐band tracking encodes sharpened signals caused by more expected phonological/morphological and semantic contents. Early presence of these effects reflects rapid computations of sharpening and prediction errors. Moreover, by measuring changes in EEG alpha power, we did not find evidence that the observed effects can be solitarily explained by attentional demands or listening efforts. Finally, we used directed information analyses to illustrate feedforward and feedback information transfers between prediction errors and sharpening across linguistic levels, showcasing how our results fit with the hierarchical Predictive Coding framework. Together, we suggest the distinct roles of delta and theta neural tracking for sharpening and predictive coding of multi‐level speech features during spoken language processing

A Self-Consistent Model For Directional Dependence Of Crack Growth

Fracture growth is considered as the competition between cleavage and dislocation self-organization in elastic-plastic solids. A self-consistent model is proposed to bridge the responses at relevant length scales, an elastic enclave in the immediate vicinity of crack tip, an array of disclination dipoles and macroscopic plastic deformation. The directional dependence of crack growth is studied. In the continuum limit, the flow stress is expressed by a spatial coupling in terms of a second-order gradient of the rotation strength of disclination dipoles. An estimate of the core size and the crack-tip shielding ratio is given by identification of the macroscopic plastic fields, the elastic field and the constitutive flow stress from the micromechanics consideration, on the boundary of elastic core. Strong dependence of apparent fracture toughness on the intrinsic surface energy and the ductile-to-brittle transition are examined

Mobile App Development to Increase Student Engagement and Problem Solving Skills

This paper describes a project designed to promote problem solving and critical thinking skills in a general education, computing course at an open access institution. A visual programming tool, GameSalad, was used to enable students to create educational apps for mobile platforms. The students worked on a game development project for the entire semester, incorporating various skills learned throughout the semester. Pre and post quiz analysis showed a significant improvement in students’ ability to design comprehensive solutions to a given problem. Survey results also showed increased student engagement, high interest in computing and a “better” understanding of information technology