Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C

Demonstration of SiC Pressure Sensors at 750 C

We report the first demonstration of MEMS-based 4H-SiC piezoresistive pressure sensors tested at 750 C and in the process confirmed the existence of strain sensitivity recovery with increasing temperature above 400 C, eventually achieving near or up to 100% of the room temperature values at 750 C. This strain sensitivity recovery phenomenon in 4H-SiC is uncharacteristic of the well-known monotonic decrease in strain sensitivity with increasing temperature in silicon piezoresistors. For the three sensors tested, the room temperature full-scale output (FSO) at 200 psig ranged between 29 and 36 mV. Although the FSO at 400 C dropped by about 60%, full recovery was achieved at 750 C. This result will allow the operation of SiC pressure sensors at higher temperatures, thereby permitting deeper insertion into the engine combustion chamber to improve the accurate quantification of combustor dynamics

Characterization of Silicon Carbide Pressure Sensors at 800 C

We have performed the initial characterization of single crystal 4H silicon carbide (4H-SiC) pressure sensors to determine the operational reliability over time at 800 C. Important parameters such as the zero pressure offset, bridge resistance, and pressure sensitivity as they are affected by temperature were extracted. These parameters showed relative stability within the prescribed operational envelop of the sensor at 800 C. Of significance is the increase in pressure sensitivity with increasing temperature beyond 400 C, to the extent that the sensitivity at 800 C was higher than the room temperature value. The implication of this result is that the sensor can be inserted further into the high temperature environment, thereby capturing the wider bandwidth of the pressure transients than currently possible

High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity

ДOCBIДЛIКУBAHHЯ BУЛЬBOBAГIHITIB ПОЄДНАНИХ З ДИСПЛАЗІЯМИ ШИЙКИ МАТКИ.

To study the ciinicai and iaboratory efficacy and safety of vaginai use of the Lomeksin for the treatment of vuivovaginitis caused by Candida and microbiaiassociations in conjunction with squamous cervicai dyspiasia there were examined and treated 5O patients aged 18 to З? years, mean age was 2З,9±5,4 years. Vuivoginitis, caused by fungi, vegetating in the form of yeast, budding fungi and in the form of myceiium, diagnosed in 1З.8 % microscopy of vaginai smears . However, oniy in 5O.O %of patients we diagnosed opportunistic fiora in the form of Gram-positive coccus, and the compiete absence of Doderiein baciiiusat54.O % and their faiiure in44.O % of patients. In our opinion, suchmicrobiocenosis of vagina preciudes therapeutic purposes preparations containing antibiotics. Ciinicai and iaboratory efficacy of the Lomeksin for vuivoginitis treatment caused by yeast fungi in vegetative forms, in conjunction with opportunistic coccai fiora was 94.O %. High efficacy, toierabiiity, ease of use, avaiiabiiity of dosage forms for simuitaneous treatment of sexuai partners and the absence of side effects can be recommended for wide use in ciinicai practice.С целью изучения клинической и лабораторной эффективности и безопасности вагинального применения препарата Ломексин для лечения вульвовагинитов, обусловленных кандидами и микробными ассоциациями в сочетании с плоскоклеточной дисплазией шейки матки обследовано и пролечено 5O больных в возрасте от 18 до З? лет, средний возраст составил 2З,9±5,4 лет. Byльвoгиниты, обусловленные грибами, вегетирующими в форме дрожжей , грибами почкующимися и в форме мицелия, диагностируются в 1З,8 % микроскопий влагалищных мазков. При этом лишьу 5O,O % больных диагностируется условно-патогенная флора ввиде грамположительных кокков, а полное отсутствие палочек Додерлейна у 54,O % и их недостаточность у 44,O % больных. По нашему мнению, подобный микробиоценоз влагалища исключает возможность применения с лечебной целью препаратов, содержащих антибиотики. Клиническая и лабораторная эффективность применения препарата Ломексин для лечениявульвогинитив, обусловленных дрожжевыми грибами в вегетирующих формах, в комплексе с условно-патогенной кокковой флорой составляла 94,O %. Bыcoкaя эффективность препарата, хорошая переносимость, удобство применения, наличие лекарственных форм для одновременного лечения половых партнеров и отсутствие побочных эффектов позволяют рекомендовать его для широкого использования в клинической практике. З метою вивчення клінічної та лабораторної ефективності і безпечності вагінального застосування препарату Ломексин для лікування вульвовагінітів, обумовлених кандидами і мікробними асоціаціями в сполученні з плоскоклітинними дісплазіями шийки матки обстежено іпроліковано 5O хворих віком від 18 до З? років, середній вік склав 2З,9±5,4 років. Byльвoгiнiти, які обумовлені грибами, що вегетуютьу формі дріжджів, грибами, що брунькуються, й у формі міцелію, діагностуються у 1З,8 % мікроскопій вагінальних мазків. При цьому тільки у 5O,O % хворих діагностується умовно-патогенна флора у вигляді грампозитивних коків, а повна відсутність паличок Додерлейна у 54,O % і їхня недостатність у 44,O % хворих. На нашу думку, подібний мікробіоценоз піхви виключає можливість застосування з лікувальною метою препаратів, які містять антибіотики. Клінічна і лабораторна ефективність застосування препарату Ломексин для лікування вульвогінітів, обумовлених дріжджовими грибами у формах, що вегетують, в комплексі з умовно-патогенною коковою флорою становила 94,O %. Bиcoкa ефективність препарату, добра переносність,зручність застосування, наявність лікарських форм для одночасного лікування статевих партнерів та відсутність побічних ефектів дозволяють рекомендувати його для широкого використання у клінічній практиці

Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented

Haemodialysis-related headache

Dialysis may induce severe headache as a result of a large amount of water and electrolyte shifts. It is important to recognize it because it can be a great problem to the patient and changing dialysis parameters or methods can prevent it. In this study we investigated the frequency and clinical characteristics of headaches occurring during haemodialysis (HD). Thirty female and 33 male patients with chronic renal failure on regular dialysis for at least 6 months in the HD unit of the Internal Medicine Department from 1996 to 2000 participated in the study. The dialysis solution contained acetate in 35 patients and bicarbonate in 28 patients. In all patients capillary dialysers and Cuprophan membranes were used and every session of dialysis lasted 4 h. All patients received the same questionnaire and they were visited randomly. Dialysis headache (DH) diagnosis was made according to the criteria of the International Headache Society. Patients with primary headache and under drug treatment during HD, which can cause headache, were excluded from the study. The frequency of DH, its relation to gender, age, dialysis technique and parameters and its features were investigated. DH was detected in 48% (n=30) of the study group. Compared with dialysis solutions, no difference was found between patients with and without DH. The difference in the pre- and post-dialysis value of urea in patients with DH was statistically significant (P<0.05). Patients with DH showed significantly higher mean systolic and diastolic blood pressure predialysis values in comparison with patients without DH (systolic, P<0.001; diastolic, P<0.01), whereas post-treatment values did not differ between the two groups. Fronto-temporal location, moderate severity, throbbing quality and short duration (<4 h) were the most prevalent features of DH in patients