Non-linear performance of a three-bearing rotor incorporating a squeeze-film damper

This paper is concerned with the non-linear vibration performance of a rigid rotor supported on three bearings, one being surrounded by a squeeze-film damper. This damper relies on the pressure built up in the squeeze film to help counter-act external forces arising from unbalance and other effects. As a result a vibration orbit of a certain magnetude results. Such vibration orbits illustrate features found in other non-linear systems, in particular sub-harmonic resonances and jump phenomena. Comparisons between theoretical prediction and experimental observations of these phenomena are made

Imaging capability of pseudomorphic high electron mobility transistors, AlGaN/GaN, and Si micro-Hall probes for scanning Hall probe microscopy between 25 and 125°C

The authors present a comparative study on imaging capabilities of three different micro-Hall probe sensors fabricated from narrow and wide band gap semiconductors for scanning hall probe microscopy at variable temperatures. A novel method of quartz tuning fork atomic force microscopy feedback has been used which provides extremely simple operation in atmospheric pressures, high-vacuum, and variable-temperature environments and enables very high magnetic and reasonable topographic resolution to be achieved simultaneously. Micro-Hall probes were produced using optical lithography and reactive ion etching process. The active area of all different types of Hall probes were 1×1 µm2. Electrical and magnetic characteristics show Hall coefficient, carrier concentration, and series resistance of the hall sensors to be 10 mOmega/G, 6.3×1012 cm−2, and 12 kOmega at 25 °C and 7 mOmega/G, 8.9×1012 cm−2 and 24 kOmega at 125 °C for AlGaN/GaN two-dimensional electron gas (2DEG), 0.281 mOmega/G, 2.2×1014 cm−2, and 139 kOmega at 25 °C and 0.418 mOmega/G, 1.5×1014 cm−2 and 155 kOmega at 100 °C for Si and 5–10 mOmega/G, 6.25×1012 cm−2, and 12 kOmega at 25 °C for pseudomorphic high electron mobility transistors (PHEMT) 2DEG Hall probe. Scan of magnetic field and topography of hard disc sample at variable temperatures using all three kinds of probes are presented. The best low noise image was achieved at temperatures of 25, 100, and 125 °C for PHEMT, Si, and AlGaN/GaN Hall probes, respectively. This upper limit on the working temperature can be associated with their band gaps and noise associated with thermal activation of carriers at high temperatures

Variable temperature-scanning hall probe microscopy with GaN/AlGaN two-dimensional electron gas (2DEG) micro hall sensors in 4.2-425K range using novel quartz tuning fork AFM feedback

In this report, we present the fabrication and variable temperature (VT) operation of Hall sensors, based on GaN/AlGaN heterostructure with a two-dimensional electron gas (2DEG) as an active layer, integrated with Quartz Tuning Fork (QTF) in atomic force-guided (AFM) scanning Hall probe microscopy (SHPM). Physical strength and wide band gap of GaN/AlGaN heterostructure makes it a better choice to be used for SHPM at elevated temperatures, compared to other compound semiconductors (AlGaAs/GaAs and InSb), which are unstable due to their narrower band gap and physical degradation at high temperatures. GaN/AlGaN micro Hall probes were produced using optical lithography and reactive ion etching. The active area, Hall coefficient, carrier concentration and series resistance of the Hall sensors were ~14m x 14m, 10m7/G at 4.2K, 6.3 x 10^12cm-2 and 12k7 at room temperature and 7m7/G, 8.9 x 10^12cm-2 and 24k7 at 400K, respectively. A novel method of AFM feedback using QTF has been adopted. This method provides an advantage over STM feedback, which limits the operation of SHPM the conductive samples and failure of feedback due to high leakage currents at high temperatures. Simultaneous scans of magnetic and topographic data at various pressures (from atmospheric pressure to high vacuum) from 4.2K to 425K will be presented for different samples to illustrate the capability of GaN/AlGaN Hall sensors in VT-SHP

Damping capacity of a sealed squeeze film bearing

The advantages of incorporating an open-ended or weakly-sealed squeeze-film bearing in a flexible support structure simulating an aero-engine assembly were examined. Attention is given to empirically modelling the hydrodynamics of the more usual tightly-sealed squeeze-film bearing, with a view to assessing its damping performance

Inequality and Discrimination in Biomedical Enhancement

In this thesis I discuss how existing inequlity and discrimination has shaped the discourse on biomedical enhancement and how the bioenhancement project can potentially exasperate them. In chapter one I discuss the most common objections against bioenhancement which include issues pertaining to cheating, praisworthyness, altering the nature of activities, coercion, quick fixes, distributive justice and authenticity. I then turn to ask why bioenhancement is desirable. I argue that bioenhancement proponents uphold a narrow understanding of autonomy, namely as control and increased choices which becomes a criterion for a good life. As such, cognitive capacities are desirable to the extent that they increase autonomy and wellbeing. In chapter two I continue this thread to argue that bioenhancement advocates understand disability as inherently bad to the extent that it is incompatible with autonomy as they envision it. To assess this claim I discuss different models of disability and argue in favor of a model of disability as neutral simpliciter. In the final chapter I discuss the issue of moral status as it is a key way in which the bioenhancement literature envisions future challenges in terms of equality. I explore the similarities in how moral status is discussed within animal ethics and within the bioenhancement literature. I explore how disability and animality are constructed as problems that biomedical enhancement can address and I conclude that biomedical enhancement is inherently incompatible to disability justice

Prophet TradItion AGAINS Fake News: FORMULATION OF FAKE NEWS EXAMINATION METHOD BASED ON ULUM AL-HADITS

The spread of fake news through social media has become a global problem and presents disorientation of knowledge or post-truth. This study aims to reveal the Jarh al-Ta'dil formula in spreading fake news. From this research, the Qur'an instructs Muslims to verify the source of all information they receive before believing it to be true:' (QS. Al-hujurat: 6). Muslims should not act on unverified sources and must legalize all information. Islam prohibits Muslims from sharing unverified information. When receiving it with your tongue and saying with your mouth what you do not know and take for granted, it is extraordinary in the sight of Allah. The formulation of the ulumul hadith method for dealing with recent fake news Several methods of criticizing fake news resulted from this hadith critique metho

Reevaluating Gender Dynamics: A Critical Analysis of Misogynistic Narratives in Hadith Literature

The discourse on religion and feminism often includes an analysis of the social construction of women in religious teachings. Feminist scholars argue that religious doctrines and interpretations, including those in Islam, have historically propagated subordinate views of women. This study examines such perceptions within Islamic Hadiths, specifically focusing on hadiths deemed misogynistic, as reported by al-Nasā’ī and other primary sources. This qualitative study employs a bibliographic approach, scrutinizing the authenticity and contextual meaning of the Hadiths. It involves a critical examination of the chain of transmission (sanad) and the text (matan) of the hadiths. The study also considers the historical and cultural context of these narrations and engages feminist perspectives to offer alternative interpretations. The hadiths from al-Nasā’ī are generally classified as hasan (sound), based on the credibility of the narrators. Variations in the text across different reports are critically examined for consistency in meaning. The study finds that while the hadiths reflect the patriarchal culture of their time, their interpretation is subject to the context and can align with Islamic teachings on justice and gender equality. The analysis suggests that these Hadiths, when contextualized, do not inherently convey misogynistic intentions. The study concludes that the perception of misogyny in the hadiths is influenced by their interpretation and historical context. A more nuanced understanding reveals that these hadiths can be interpreted in ways that support harmony and equality within the family, aligning with broader Islamic principles

Pengaruh Model Pembelajaran terhadap Kemampuan Memecahkan Masalah Lingkungan Hidup pada Siswa yang Mempunyai Hasil Belajar IPA Tinggi di Sekolah Dasar

The aim of the research is to identify the influence of learning model and IPA Science learning on the ability to solve problem in learning environmental education at the elementary school. This research was conducted in SD Laboratorium UPI Kampus Cibiru Bandung. Experimental method with factorial plan 2 x 2 is the method that was employed in this study. The sampling objects were 40-fourth grade students. Twenty of them achieved high learning outcomes in environmental study meanwhile the remains were having low learning outcomes. Two ways varian analysis (ANAVA) was used in hypothesis test and then continued by Turkey test. The research conclusion were: Students with high learning outcomes in science had better ability to solve environmental problems using constructivist learning model than interactive learning model

Pemahaman Konsep Tubuh Manusia dan Kesulitan - Kesulitan dalam Menguasainya pada Mahasiswa Program S-1 PGSD UPI Kampus Cibiru

Secara umum penelitian ini bertujuan untuk mencari alternatif program perkuliahan di Program S1 PGSD UPI Kampus Cibiru, secar khusus penelitian ini dilaksanakan untuk mengetahui tingkat penguasaan konsep IPA , khususnya pada sub konsep tubuh manusia mahasiswa Program S1 PGSD UPI Kampus Cibiru, memperoleh informasi tentang kesulitan-kesulitan yang dialami oleh mahasiswa, dan memperoleh ionformasi tenatng faktor-faktor yang menyebabkan kesulitan belajar mahasiswa

Menggugah Kepedulian Siswa terhadap Satwa Liar melalui Pendidikan IPA di Sekolah Dasar

Kepedulian terhadap satwa liar ini harus ditanamkan sejak dini, agar dalam setiap gerak kehidupan sesuai dengan perkembangan usia manusia, mereka selalu menaruh perhatian terhadap satwa liar dalam bentuk tindakan kongkrit, yang dapat ikut mencegah kepunahan satwa liar. Penanam kepedulian terhadap satwa liar sejak usia dini dapat dilakukan dengan berbagai cara. Salah satu cara yang menurut penulis tepat adalah dengan pendidikan, khususnya melalui pendidikan IPA di sekolah dasar. Pendidikan IPA di Sekolah Dasar dapat digunakan untuk menanamkan kepedulian siswa terhadap satwa liar sejak dini. Kepedulian terhadap satwa liar tersebut dapat dimasukkan dalam bahan ajar yang menyangkut tentang Makhluk hidup dan proses kehidupannya, yaitu manusia, hewan, tumbuhan, dan interaksinya. Permasalahannya adalah, tindakan konkrit apa yang harus dilakukan oleh para praktisi pendidikan dalam melaksanakan kegiatan pembelajaran IPA di sekolah dasar, dalam materi-materi terkait, sehingga dapat menanamkan kepedulian siswa terhadap satwa liar sejak usia dini