Rotor bearing systems (RBSs) play a very valuable role for wind turbine gearboxes, aero−engines, high speed spindles, and other rotational machinery. An in−depth understanding of vibrations of the ...RBSs is very useful for condition monitoring and diagnosis applications of these machines. A new twelve−degree−of−freedom dynamic model for rigid RBSs with a localized defect (LOD) is proposed. This model can formulate the housing support stiffness, interfacial frictional moments including load dependent and load independent components, time−varying displacement excitation caused by a LOD, additional deformations at the sharp edges of the LOD, and lubricating oil film. The time−varying displacement model is determined by a half−sine function. A new method for calculating the additional deformations at the sharp edges of the LOD is analytical derived based on an elastic quarter−space method presented in the literature. The proposed dynamic model is utilized to analyze the influences of the housing support stiffness and LOD sizes on the vibration characteristics of the rigid RBS, which cannot be predicted by the previous dynamic models in the literature. The results show that the presented method can give a new dynamic modeling method for vibration formulation for a rigid RBS with and without the LOD on the races.
•A new 12DOF dynamic model for a rigid rotor bearing system is proposed.•Time-varying excitations caused by a localized defect are formulated.•A new method is presented to calculate additional deformations at defect sharp edges.•Effects of housing support stiffness and defect sizes on vibrations of the system is studied.
The Jewish-Arab City Yacobi, Haim
2009, 20090317, 2009-03-17, 20090101, Letnik:
5
eBook
Mixed city is a term widely used in Israel to describe areas occupied by both Jewish and Arab communities. In a critical examination of such cities, the author shows how a clear spatial and mental ...division exists between Arabs and Jews in Israel, and how the occurrence of such communities is both exceptional and involuntary.
Looking at Jewish-Arab relations in Israel in the context of the built environment, it is argued that there are complex links between socio-political relations and the production of contested urban space. The case study of one particular Jewish-Arab "mixed city", the city of Lod, is used as the platform for wider theoretical discussion and political analysis. This city has great significance in the present global context, as more and more cities are becoming polarized, ghettoized, and fragmented in surprisingly similar ways. This book examines the visible planning apparatuses and the "hidden" mechanisms of social, political, and cultural control involved in these processes.
Focusing on the spatialities of power, this book brings to the fore a critical discussion of the urban processes that shape Jewish-Arab "mixed cities" in Israel, and will be of interest to students and scholars of Urban Studies, Middle East Studies and Politics in general.
Introduction 1. Orientalism, Modernity and Urban Design in Mandatory Lydda 2. From al-Ludd to Lod 3. Architecture and the Struggle over Geography 4. Territorialization and the City's Geopolitics of Fear 5. Agents, Enemies, and the Privatization of Space 6. Walking, Inhabiting, Narrating. Conclusion
Haim Yacobi is an architect and lecturer at the Department of Politics and Government at Ben-Gurion University. His main research interests are the production of urban space, social justice, the politics of identity, migration, globalization and urban planning.
H2 gas sensors for different applications require various detection ranges, such as 1–100 ppm for exhale breath test and 0–40000 ppm for H2 energy vehicles. Coarse-tuning of the detection range could ...be realized by the selection of the type of H2 sensors. The fine-tuning of the detection range within one type of H2 sensor, however, is little concerned and reported. Herein, we propose to achieve the fine-tuning of the H2 gas detection range of the AlGaN/GaN HEMT devices by adjusting the Pt gate thickness. Devices with various Pt gate thicknesses of 2, 20, 60, and 100 nm were fabricated and investigated. Results show that the HEMT devices have excellent pinch-off characteristic with an on-to-off ratio of ∼four orders of magnitude. For the 100 nm thick device exposed to 500 ppm H2, ultrafast response time of 1.5 s is observed together with high response. With the decrease of gate thickness, both the response and the response time gradually increase, 1850% and 6 s for the 2 nm thick device. Moreover, both the low limit of detection (LOD) and the saturation cencentration decrease from 1.6 to 0.14 ppm and from 30,000 to 5000 ppm, respectively, with the gate thickness reduced from 100 to 2 nm, revealing that fine-tuning of the detection range could be achieved by adjusting the gate thickness. Finally, the response activation energy is also studied, 15.9, 19.7, and 42.8 kJ/mol for 2, 60, and 100 nm thick devices, respectively.
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•Employment of AlGaN/GaN HEMT device as a H2 gas sensor.•Demonstration of a high performance H2 sensor with small LOD ∼0.14 ppm and ultrafast response ∼1.5 s.•Realization the fine-tuning of the detection range by simply adjusting the gate thickness.•Study the dependence of the response activation energy Ea on the gate thickness.
In the early building design stage, there are numerous uncertainties due to the lack of information on materials and processes. Designers therefore cannot quantify the environmental impacts of ...buildings in order to evaluate the environmental performance of their designs early on. In this paper, life cycle assessment (LCA) and building information modeling (BIM) are carried out in the early and detailed building design stages. The method is applied to a residential building in Québec, Canada. The BIM is conducted with Revit, and the LCA with openLCA. To prepare the Revit outputs as the appropriate inputs of the LCA model, a functional database was developed. It includes all building assemblies, layers and possible materials commonly found in residential buildings in Québec. The ecoinvent database was used to source of life cycle inventory (LCI) data for each material. To manage information uncertainty in the early design stage, a probability function was assigned to each material. At the detailed design stage, all material types and quantities were specified in BIM file, which was used in the LCA study. The environmental impacts of the building stages and assemblies were calculated to determine the best building assembly options from an environmental perspective—a process that could guide building designers in the environmental assessments of their designs, making it possible to select more sustainable materials for each assembly and thus reduce the environmental impacts of the building.
•An integration of BIM and LCA are carried out in residential buildings.•Both early and detailed building design stages are considered.•A technique to assess environmental performance of buildings is proposed.•The best building materials options from environmental perspective are specified.
The high toxicity of hexavalent chromium Cr (VI) could not only cause harmful effects on humans, including carcinogenicity, respiratory issues, genetic damage, and skin irritation, but also ...contaminate drinking water sources, aquatic ecosystems, and soil, impairing the reproductive capacity, growth, and survival of organisms. Due to these harmful effects, detecting toxic Cr (VI) is of great significance. However, the rapid, simple, and efficient detection at a low Cr (VI) concentration is extremely challenging, especially in an acidic condition (existing as HCrO4−) due to its low adsorption free energy.
A diketopyrrolopyrrole-based small molecule (DPPT-PhSMe) is designed and characterized to act as a chemosensor, which allows a high selectivity to Cr (VI) at an acidic condition with a low limit of detection to 10−8 M that is two orders of magnitude lower than the cut of limit (1 μM) recommended by World Health Organization (WHO). Mechanism study indicates that the rich sulfur atoms enhance the affinity to HCrO4−. Combining with favorable features of diketopyrrolopyrrole, DPPT-PhSMe not only allows dual-mode detection (colorimetric and spectroscopic) to Cr (VI), but also enables disposable paper-based sensor for naked-eye detection to Cr (VI) from fully aqueous media. The investigation of DPPT-PhSMe chemosensor for the quantification of Cr (VI) in real life samples demonstrates a high reliability and accuracy with an average percentage recovery of 102.1 % ± 4 (n = 3).
DPPT-PhSMe represents the first diketopyrrolopyrrole-derived chemosensor for efficient detection to toxic Cr (VI), not only providing a targeted solution to the bottleneck of Cr (VI) detection in acidic conditions (existing as HCrO4−) caused by its low adsorption free energy, but also opening a new scenario for simple, selective, and efficient Cr (VI) detection with conjugated dye molecules.
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•A first diketopyrrolopyrrole-derived chemosensor (DPPT-PhSMe) for toxic Cr (VI) detection is designed and characterized.•The chemosensor provides a targeted solution to the bottleneck of HCrO4− detection caused by low adsorption free energy.•DPPT-PhSMe allows a low LOD to Cr (VI) detection of 10−8 M and an accurate quantitative analysis in real world samples.•This work opens a new scenario for simple, selective and efficient Cr (VI) detection with conjugated dye molecules.
This paper reports on the advanced development of an ultrasensitive method for the detection of benzene, toluene, and ethylbenzene (or BTE) by low-pressure photoionization mass spectrometry ...(LPPI-MS). The LPPI source is composed of a laboratory-assembled krypton lamp and a stainless steel cylindrical ionizer. A compact V-shaped mass spectrometer is coupled to the LPPI source with a set of ion immigration optics under dc bias. The fixed standard concentration (FSC) and fixed standard volume (FSV) method are employed to calibrate the sensitivities of the instrument. The corresponding detection sensitivity toward BTE is 4–7 counts/pptv and the 2σ limit of detection (LOD) is 0.5–0.8 part per trillion by volume (pptv). In addition, the measurement accuracy is 95%–105%, and the corresponding precision ranges from 3% to 15% and from 9% to 31% for the FSC and FSV methods, respectively. The stability (standard deviation) of LPPI-MS for a 1 ppbv BTE mixture is less than 0.025 (>12 h). In the detection of BTE, water in ambient air is the most significant interfering factor, leading to the increased background, and inferior LODs of 1–2 pptv for BTE under an RH of ∼90% is observed. Experimental results indicated that LPPI-MS is reliable for the detection of sub-pptv levels of BTE under laboratory conditions.
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•LPPI mass spectrometry were demonstrated to be ultrasensitive for realtime detection.•The obtained LODs are superior to those of other competitive techniques.•Limits of detection for benzene, toluene, and ethylbenzene are 0.5–0.8 pptv.•Detection sensitivities for benzene, toluene, and ethylbenzene are 4–7 counts/pptv.•Reliable accuracy and precision are demonstrated in two calibration methods.
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•Synthesized imidazole-based Schiff base ligand (Z)-N’-((1H-imidazol-2-yl)methylene)-2-hydroxybenzohydrazide (IMBH).•IMBH was used as a selective and sensitive probe for detection of ...Cu2+ and Fe2+ ions.•The limit of detection (LOD) was found to be 4.10 × 10−7 M and 6.01 × 10−7 M, for Cu2+ and Fe2+ ions, respectively.•IMBH was successfully utilized for the quantitative analysis of Cu2+ and Fe2+ ions in real water samples and logic gate construction.
A novel imidazole-based Schiff base ligand (Z)-N’-((1H-imidazol-2-yl)methylene)-2-hydroxybenzohydrazide (IMBH), was effectively synthesized and characterized using spectroscopic methods. Chemosensor IMBH’s chelation enhanced fluorescence (CHEF) is responsible for its extremely selective and sensitive detection of Cu2+ and Fe2+ ions in DMSO solutions. Adding different metal ions (30 μM) allowed for the determination of the fluorescence behaviour of IMBH (50 μM). The findings showed that, only for Cu2+ and Fe2+ ions, a notable fluorescence quenching in the emission was seen at 465 nm with an excitation at 320 nm. Furthermore, the Job’s plot and mass spectral analysis showed that IMBH bound Cu2+ and Fe2+ ions at a 2:1 (Ligand:Metal) ratio. For the Cu2+ and Fe2+ ions, the limit of detection (LOD) was found to be 0.204 × 10−9 M and 0.201 × 10−9 M, respectively. On the other hand, IMBH was successfully utilized for the quantitative analysis of Cu2+ and Fe2+ ions in real water samples and logic gate construction. In addition, optoelectronic and structural properties of the IMBH and Fe(II) and Cu(II) complexes were determined by solvent phase DFT calculations.
•Successfully synthesized and characterized a new chemosensor, CQMAP, specifically designed for Cr(III) detection.•Comprehensive characterization using NMR and FT-IR confirms the structure and purity ...of CQMAP.•Remarkable sensitivity, detecting Cr(III) at concentrations as low as 14.70 µM.•Highly selective for Cr(III) even in the presence of various competing cations.•The Cr(III)-CQMAP complex formation follows a 1:3 stoichiometry.•The binding constant (1.73×10^4 M^−1) indicates a strong interaction between Cr(III) and CQMAP.•This work presents a novel, highly sensitive, and selective chemosensor for Cr(III) detection with promising applications in environmental monitoring and analytical chemistry.
In this investigation, a new Cr(III)-chemosensor, 2-{(2-chloroquinolin-3-yl)methylideneamino}phenol (CQMAP), had been successfully synthesized and characterized. The new chemosensor had been characterized using both NMR and FT-IR spectroscopy techniques. The CQMAP showcased remarkable sensitivity & selectivity, specifically against Cr(III) ions in aqueous media, even when challenged with various competing cations, such as Na(I), Mg(II), Al(III), K(I), Ca(II), Mn(II), Fe(II), Co(II), Ni(II), Zn(II), Sr(II), Ag(I), Cd(II), and Pb(II) respectively. The improved chemosensor underwent a distinctive colour transition to pale blue, offering a simple, clear and straightforward indication of Cr(III) presence. The CQMAP demonstrated a colorimetric assay for the optical/visual detection of Cr(III) ions with a detection limit of 14.65 ± 1.02 µM. The sensing action had been proposed by the formation of a complex with Cr(III) in a 1:3 stoichiometry (Cr(III) : CQMAP). Furthermore, the synthesized CQMAP underwent a meticulous characterization process using FT-IR, mass, Uv-vis. Spectroscopy, Thermal, conductivity, and magnetic behaviour measurements. The CrCQMAP complex had a binding constant of 1.84±1.21×104 M−1, forming a 1:3 stoichiometry with Cr(III) ions, providing insights into the strength of the interaction. These findings collectively underscore the robustness and versatility of CQMAP as an effective chemosensor for Cr(III) detection, showcasing its potential across diverse applications, including environmental monitoring and analytical chemistry.
Ag+ ions can be colorimetric and fluorometrically detected in the aqueous acetonitrile medium with great selectivity using TOV. Observable to the naked eye, the synthesized compound exhibited an ...amazing fluorometric reaction in the presence of Ag+, changing from colorless to yellow. We examine the suggested Ag+ sensor's analytical performance characteristics with a considerable detection limit of 6.138×10−9 M. The chemosensor can be used for Ag+ measurement. According to the experiment results, TOV's fluorometric response to Ag+is pH-dependent throughout a broad pH range of 1.0 to 10.0. Furthermore, EDTA can be used to repeatedly reverse the Fluorometric reaction of TOV + Ag+. Job's plot, HRMS, and 1H NMR titration experiments have all been used to study the mechanism of interaction between the TOV and Ag+ ions. These studies have validated the 1:2 binding stoichiometry between TOV and Ag+. Test paper-based detection, Measuring Ag+ in water samples, were three examples of the real-time use of Ag+detection and chemosensor was used in MCF7 cells to assess cytotoxicity.
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