42 research outputs found
Single- and dual-feedback transimpedance amplifiers implemented by SiGe HBT technology
No full textMonolithically integrated SiGe/Si heterojunction bipolar transistor (HBT) transimpedance amplifiers, with single-and dual-feedback configurations, have been designed, fabricated, and characterized, The single-feedback amplifier showed transimpedance gain and bandwidth of 45.2 dB Omega and 3.2 GHz, respectively, The dual-feedback version exhibits improved gain and bandwidth of 47.4 dB Omega and 3.3 GHz, respectively, Their performance characteristics are excellent in terms of their application in communication systems.NASA-Cleveland under Grant NAG3-1903 and by the AFOSR under Grant F49620-95-1-0013
Investigation of adjacent channel crosstalk in multichannel monolithically integrated 1.55 mu m photoreceiver arrays
No full textWe have investigated adjacent channel crosstalk in 3-, 8-, and 16-channel InP-based monolithically integrated p-i-n/HBT photoreceiver arrays, with a channel bandwidth of 11 GHz, By using a novel monolithically integrated radiation shield, we have been able to reduce the crosstalk to -35 dB at 10 GHz, These parameters represent the best performance in multichannel integrated photoreceiver arrays, The two main components of crosstalk are found to be radiation crosstalk and electrical crosstalk and these are separately dependent on interchannel spacing and single-or dual-source biasing schemes. A electromagnetic full-wave solution shows that the measured crosstalk in arrays without the radiation shield could be dominated by radiation crosstalk, which can be modeled as a capacitive coupling between adjacent channels, Similarly, electrical crosstalk can be modeled by equivalent parasitic resistive and inductive elements, Values of these circuit elements have been determined by analyzing experimental data.Defense Advanced Research Projects Agency (COST) Grant MDA 972-94-1-0004, and the U.S. Army Research Office (URI program) Grant DAAL03-92-G-010
Monolithically integrated SiGe-Si PIN-HBT front-end photoreceivers
No full textFabrication and characterization of monolithically integrated SiGe-Si PIN-HBT transimpedance photoreceivers are reported, SiGe-Si technology has been developed leading to SiGe-Si HBT's with f(T) = 23 GHz and f(max) = 34 GHz, and to PIN photodiodes with responsivity of 0.3 A/W at lambda = 850 nm and bandwidth of 450 MHz, SiGe-Si HBT transimpedance amplifiers showed transimpedance gain of 52.2 dB.Omega and bandwidth of 1.6 GHz, and the photoreceivers exhibited the bandwidth of 460 MHz.NASA-Cleveland under Grant NAG3-1903 and by
the Air Force of Scientific Research under Grant F49620-95-1-001
An integral formulation of two- and three-dimensional dielectric structures using orthonormal multiresolution expansions
No full text
Flexural strength and rotation capacity of welded I-section steel beams with longitudinally profiled flanges
No full textApplication of longitudinally profiled (LP) steel plate in the flange of flexural members may provide a good solution to optimize their mechanical performance and to improve the efficiency of steel use, whilst existing design codes provide no design guidance or prediction methodology for such advanced beams in terms of flexural behaviour. To clarify their flexural strength and rotation capacity, tests on two full-scale welded I-section steel beams with longitudinally profiled flanges (LPB members) are carried out herein, as well as two traditional beams with uniform cross-section for comparison. All the specimens exhibit sufficient flexural strength and rotation capacity for seismic plastic design, and specifically, the LPB members possess even better performance in case of identical steel usage. Parametric analyses of 250 beams incorporating a wide range of flange slenderness and steel grades, are conducted by employing the validated nonlinear FE model to investigate the effects of rate of thickness change for the LP flanges. The results show that the effect is limited on the flexural strength but significant on rotation capacity. The existing design provisions for beams with uniform cross-section give generally conservative design results for the flexural strength of the LPB members, but limiting values of flange slenderness needs to be reduced. The research outcomes may provide an important basis for promoting the application of LP plates in flexural members.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Steel & Composite Structure
Lipopeptide Biosurfactant from Acinetobacter junii B6: A Promising Natural Surfactant for Promoting Angiogenesis
No full textLipopeptide biosurfactants (LPBs) display unique properties with widespread therapeutic applications. Recently, the wound healing activity of LPBs has received more attention. However, few investigations have focused on the healing mechanisms of these compounds, particularly those that are associated with the angiogenic pathways. Therefore, the current study aimed at investigating the effect of a natural LPB produced by Acinetobacter. junii B6 on the angiogenic potential of human umbilical vein endothelial cells (HUVECs). The proliferation, migration, and three-dimensional tube forming potential of HUVECs were examined after treatment with LPB. By using western blotting, the expression of angiogenic-related genes such as hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were also measured. LPB demonstrated no significant proliferative or cytotoxic effect on HUVECs at the concentrations lower than 600 µg/mL. Moreover, LPB at a concentration of 300 µg/mL caused a significant increase in the rates of migration and tube formation of HUVECs. LPB also enhanced the protein expression levels of HIF-1α and VEGF in HUVECs in a dose-dependent manner. The present results suggest that LPB might be considered a potential wound healing agent by modifying some angiogenic factors. © 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature
Architectural patterning in the Purepecha heartland: an intrasite settlement study at the urban center of Sacapu Angamuco, Michoacán, México
No full text2012 Spring.Includes bibliographical references.The overall goal of this thesis is to examine the architectural patterns of Sacapu Angamuco (Angamuco), a recently discovered Early-Middle Postclassic (A.D. 900-1350) urban settlement in the Lake Pátzcuaro Basin (LPB), Michoacán, Mexico that is located on an ancient lava flow, or malpais, and was extensively modified by prehispanic inhabitants to construct thousands of structures such as platforms, mounds, plazas, passages, stairs, and temples. Central to this thesis is how prehispanic residents of Angamuco organized their buildings and social space. The study of architectural remains is one critical component of ancient urbanism which is fundamental to Mesoamerican societies. Angamuco provides a rich opportunity to understand urbanism in the LPB. Understanding the spatial context of buildings and how they are grouped in functionally discernable ways is crucial to interpreting the internal function(s) of the settlement, as well as contributing to regional settlement pattern analyses. This thesis incorporates intensive survey using GPS, GIS, and remote sensing to document architecture and analyze the spatial patterns of architecture at Angamuco using data from the 2010 field season. An overview of relevant definitions and approaches to Mesoamerican urban settlement studies and the study of spatial patterning and classification of architecture is presented. A description of the physical setting of the LPB and Angamuco, the cultural-historical background of the region, and background information on previous archaeological work addressing urbanism, settlement patterns, and architecture in the LPB region is discussed. The research methodology used to collect data on Angamuco's architecture and settlement patterns is reviewed. The core of this work concerns an analysis of Angamuco architecture, beginning with description of the form and function of individual architectural features and analysis of architectural group form and patterning in the study area. Finally, the analysis is synthesized with the questions guiding this research, as well as current knowledge about Postclassic urbanism in the LPB and beyond. Ultimately, it is hoped that work at Angamuco will improve understanding of Postclassic LPB architecture, settlement patterns, and the role of cities before and during the development of the Tarascan Empire
Economic financial operations evalution of company "Rendas Uplejas" LLC and development forecast
No full textDarba mērķis ir veikt uzņēmuma SIA „Rendas Upeslejas” saimnieciskās darbības analīzi, konstatēt problēmas un uz to pamata izstrādāt priekšlikumus uzņēmuma darbības pilnveidošanai.
Lai sasniegtu izvirzīto mērķi, autore darbu izstrādāja trīs nodaļās. Maģistra darba ietvaros, autore pētīja SIA „Rendas Uplejas” saimniecisko darbību, vietu Latvijas tirgū, veica SVID un saimnieciskās darbības analīzi un novērtēja uzņēmumu, salīdzinot ar mazumtirdzniecības nozares vidējiem un konkurenta AS „LPB” rādītājiem.
Maģistra darba pētījuma gaitā autore konstatēja, ka uzņēmums ir atkarīgs no aizņemtā kapitāla, ir likviditātes problēmas un ir zemi rentabilitātes rādītāji. Darba autore izstrādāja priekšlikumus uzņēmuma saimnieciskās darbības uzlabošanai.
Atslēgvārdi: saimnieciskās darbības analīze, SVID analīze, finanšu rādītāji, horizontālā analīze, vertikālā analīze, mazumtirdzniecība, konkurence.The aim of the Master thesis is to analyse the performance of "Rendas Uplejas Ltd., find the main problems and present suggestions to improve its performance.
To reach the goal, the author has organized the thesis in three chapters. The author analysed the economic activity of the enterprise and its position in the market, carried out SWOT analysis, and compared it with the average retailing indices and the indices of the competitor, stock corporation "LPB".
It was concluded that the enterprise is dependent on the debenture capital; there are liquidity issues; the indices of profitability are low. The author has presented suggestions to improve the economic activity of the enterprise.
Key words: analysis of the economic activity; SWOT analysis; financial indices; horizontal analysis; vertical analysis; retailing; competition
Tropical fruit-derived Lactiplantibacillus as potential probiotic and antifungal agents against Fusarium oxysporum
No full textFifty-five lactic acid bacteria (LAB) were isolated from seven selected tropical fruits, with Solanum nigrum exhibiting the highest LAB prevalence and Couroupita guianenis and Musa fruits showing the lowest counts. Two strains isolated from Ficus racemosa demonstrated significant antifungal activity against Fusarium oxysporum. 16S rDNA sequencing identified these strains as Lactiplantibacillus plantarum MYSVCF3 and Lpb. argentoratensis MYSVCF5. The isolates displayed adaptability to a broad range of environmental conditions, including temperatures of 10–45 °C, pH 2–6, and salt up to 7%. The strains tolerated simulated gastrointestinal conditions of acid (pH-2), phenol (0.6%), and bile (0.3%) suggesting potential probiotic attributes. Lpb. argentoratensis MYSVCF5 inhibited F. oxysporum, two ESKAPE group bacteria (P. aeruginosa, S. aureus) plus S. paratyphi and E. coli. The cell-free supernatant (CFS) of Lpb. argentoratensis MYSVCF5 reduced the growth of fungal biomass by 94% and completely inhibited conidial germination, retaining activity even after extended cold storage. LC–MS/MS analysis identified organic acids in the CFS, with citric acid as the most abundant at 34.9 (± 0.3) µg/mL, followed by lactic (8.3 µg/mL) and malic acids (5.2 µg/mL). This study isolated a novel LAB, a potential candidate having probiotics and antifungal properties for application in food and agriculture. © The Author(s) 2025
