936 resultados para Thermoelectric apparatus and appliances


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Technological developments in microprocessors and ICT landscape have made a shift to a new era where computing power is embedded in numerous small distributed objects and devices in our everyday lives. These small computing devices are ne-tuned to perform a particular task and are increasingly reaching our society at every level. For example, home appliances such as programmable washing machines, microwave ovens etc., employ several sensors to improve performance and convenience. Similarly, cars have on-board computers that use information from many di erent sensors to control things such as fuel injectors, spark plug etc., to perform their tasks e ciently. These individual devices make life easy by helping in taking decisions and removing the burden from their users. All these objects and devices obtain some piece of information about the physical environment. Each of these devices is an island with no proper connectivity and information sharing between each other. Sharing of information between these heterogeneous devices could enable a whole new universe of innovative and intelligent applications. The information sharing between the devices is a diffcult task due to the heterogeneity and interoperability of devices. Smart Space vision is to overcome these issues of heterogeneity and interoperability so that the devices can understand each other and utilize services of each other by information sharing. This enables innovative local mashup applications based on shared data between heterogeneous devices. Smart homes are one such example of Smart Spaces which facilitate to bring the health care system to the patient, by intelligent interconnection of resources and their collective behavior, as opposed to bringing the patient into the health system. In addition, the use of mobile handheld devices has risen at a tremendous rate during the last few years and they have become an essential part of everyday life. Mobile phones o er a wide range of different services to their users including text and multimedia messages, Internet, audio, video, email applications and most recently TV services. The interactive TV provides a variety of applications for the viewers. The combination of interactive TV and the Smart Spaces could give innovative applications that are personalized, context-aware, ubiquitous and intelligent by enabling heterogeneous systems to collaborate each other by sharing information between them. There are many challenges in designing the frameworks and application development tools for rapid and easy development of these applications. The research work presented in this thesis addresses these issues. The original publications presented in the second part of this thesis propose architectures and methodologies for interactive and context-aware applications, and tools for the development of these applications. We demonstrated the suitability of our ontology-driven application development tools and rule basedapproach for the development of dynamic, context-aware ubiquitous iTV applications.

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Measurement is a tool for researching. Therefore, it is important that the measuring process is carried out correctly, without distorting the signal or the measured event. Researches of thermoelectric phenomena have been focused more on transverse thermoelectric phenomena during recent decades. Transverse Seebeck effect enables to produce thinner and faster heat flux sensor than before. Studies about transverse Seebeck effect have so far focused on materials, so in this Master’s Thesis instrumentation of transverse Seebeck effect based heat flux sensor is studied, This Master’s Thesis examines an equivalent circuit of transverse Seebeck effect heat flux sensors, their connectivity to electronics and choosing and design a right type amplifier. The research is carried out with a case study which is Gradient Heat Flux Sensors and an electrical motor. In this work, a general equivalent circuit was presented for the transverse Seebeck effect-based heat flux sensor. An amplifier was designed for the sensor of the case study, and the solution was produced for the measurement of the local heat flux of the electric motor to improve the electromagnetic compatibility.

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The epidermis is the upper layer of the skin and keratinocytes are its most abundant cells. Tight junctions are cell junctions located in the granular layer of the epidermis. They maintain the polarity of the cells and regulate the movement of water-soluble molecules. Epidermal tight junctions may lose their integrity when there are defects in intercellular calcium regulation. Hailey-Hailey and Darier´s disease are dominantly inherited, blistering skin diseases. Hailey-Hailey disease is caused by mutations in the ATP2C1 gene encoding a calcium/manganese ATPase SPCA1 of the Golgi apparatus. Darier´s disease is caused by mutations in the ATP2A2 gene encoding a calcium ATPase SERCA2 of the endoplasmic reticulum. p38 regulates the differentiation of keratinocytes. The overall regulation of epidermal tight junctions is not well understood. The present study examined the regulation of tight junctions in the human epidermis with a focus on calcium ATPases and p38. Skin from Hailey-Hailey and Darier´s disease patients was studied by using immunofluorescence labeling which targeted intercellular junction proteins. Transepidermal water loss was also measured. ATP2C1 gene expression was silenced in cultured keratinocytes, by siRNA, which modeled Hailey-Hailey disease. Expression of intercellular junction proteins was studied at the mRNA and protein levels. Squamous cell carcinoma and normal human keratinocytes were used as a model for impaired and normal keratinocyte differentiation, and the role of p38 isoforms alpha and delta in the regulation of intercellular junction proteins was studied. Both p38 isoforms were silenced by adenovirus cell transduction, chemical inhibitors or siRNA and keratinocyte differentiation was assessed. The results of this thesis revealed that: i.) intercellular junction proteins are expressed normally in acantholytic skin areas of patients with Hailey-Hailey or Darier´s disease but the localization of ZO-1 expanded to the stratum spinosum; ii.) tight junction proteins, claudin-1 and -4, are regulated by ATP2C1 in non-differentiating keratinocytes; and iii.) p38 delta regulates the expression of tight junction protein ZO-1 in proliferating keratinocytes and in squamous cell carcinoma derived cells. ZO-1 silencing, however, did not affect the expression of other tight junction proteins, suggesting that they are differently regulated. This thesis introduces new mechanisms involved in the regulation of tight junctions revealing new interactions. It provides novel evidence linking intracellular calcium regulation and tight junctions.

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The objective of this work is to describe the design and the implementation of an experiment to study the dynamics and the active control of a slewing multi-link flexible structure. The experimental apparatus was designed to be representative of a flexible space structure such as a satellite with multiple flexible appendages. In this study we describe the design procedures, the analog and digital instrumentation, the analytical modeling together with model validation studies carried out through experimental modal testing and parametric system identification studies in the frequency domain. Preliminary results of a simple positional control where the sensor and the actuator are positioned physically at the same point is also described.

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The aim of the present paper is to study the relationship between the fracture modes in hydrogen-assisted cracking (HAC) in microalloied steel and the emission of acoustic signals during the fracturing process. For this reason, a flux-cored arc weld (FCAW) was used in a high-strength low-alloy steel. The consumable used were the commercially available AWS E120T5-K4 and had a diameter of 1.6 mm. Two different shielding gases were used (CO2 and CO2+5% H2) to obtain complete phenomenon characterization. The implant test was applied with three levels of restriction stresses. An acoustic emission measurement system (AEMS) was coupled to the implant test apparatus. The output signal from the acoustic emission sensor was passed through an electronic amplifier and processed by a root mean square (RMS) voltage converter. Fracture surfaces were examined by scanning electron microscopy (SEM) and image analysis. Fracture modes were related with the intensity, the energy and the number of the peaks of the acoustic emission signal. The shielding gas CO2+5% H2 proved to be very useful in the experiments. Basically, three different fracture modes were identified in terms of fracture appearance: microvoid coalescence (MVC), intergranular (IG) and quasi-cleavage (QC). The results show that each mode of fracture presents a characteristic acoustic signal.

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Initially identified as stress activated protein kinases (SAPKs), the c-Jun Nterminal kinases (JNKs) are currently accepted as potent regulators of various physiologically important cellular events. Named after their competence to phosphorylate transcription factor c-Jun in response to UVtreatment, JNKs play a key role in cell proliferation, cell death or cell migration. Interestingly, these functions are crucial for proper brain formation. The family consists of three JNK isoforms, JNK1, JNK2 and JNK3. Unlike brain specific JNK3 isoform, JNK1 and JNK2 are ubiquitously expressed. It is estimated that ten splice variants exist. However, the detailed cellular functions of these remain undetermined. In addition, physiological conditions keep the activities of JNK2 and JNK3 low in comparison with JNK1, whereas cellular stress raises the activity of these isoforms dramatically. Importantly, JNK1 activity is constitutively high in neurons, yet it does not stimulate cell death. This suggests a valuable role for JNK1 in brain development, but also as an important mediator of cell wellbeing. The aim of this thesis was to characterize the functional relationship between JNK1 and SCG10. We found that SCG10 is a bona fide target for JNK. By employing differential centrifugation we showed that SCG10 co-localized with active JNK, MKK7 and JIP1 in a fraction containing endosomes and Golgi vesicles. Investigation of JNK knockout tissues using phosphospecific antibodies recognizing JNK-specific phosphorylation sites on SCG10 (Ser 62/Ser 73) showed that phosphorylation of endogenous SCG10 was dramatically decreased in Jnk1-/- brains. Moreover, we found that JNK and SCG10 co-express during early embryonic days in brain regions that undergo extensive neuronal migration. Our study revealed that selective inhibition of JNK in the cytoplasm significantly increased both the frequency of exit from the multipolar stage and radial migration rate. However, as a consequence, it led to ill-defined cellular organization. Furthermore, we found that multipolar exit and radial migration in Jnk1 deficient mice can be connected to changes in phosphorylation state of SCG10. Also, the expression of a pseudo-phosphorylated mutant form of SCG10, mimicking the JNK1- phopshorylated form, brings migration rate back to normal in Jnk1 knockout mouse embryos. Furthermore, we investigated the role of SCG10 and JNK in regulation of Golgi apparatus (GA) biogenesis and whether pathological JNK action could be discernible by its deregulation. We found that SCG10 maintains GA integrity as with the absence of SCG10 neurons present more compact fragmented GA structure, as shown by the knockdown approach. Interestingly, neurons isolated from Jnk1-/- mice show similar characteristics. Block of ER to GA is believed to be involved in development of Parkinson's disease. Hence, by using a pharmacological approach (Brefeldin A treatment), we showed that GA recovery is delayed upon removal of the drug in Jnk1-/- neurons to an extent similar to the shRNA SCG10-treated cells. Finally, we investigated the role of the JNK1-SCG10 duo in the maintenance of GA biogenesis following excitotoxic insult. Although the GA underwent fragmentation in response to NMDA treatment, we observed a substantial delay in GA disintegration in neurons lacking either JNK1 or SCG10.

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(Ultrastructure of secretory and senescence phase in colleters of Bathysa gymnocarpa and B. stipulata (Rubiaceae)). Colleters are secretory structures formed by a parenchymatic axis with vascular bundles, bound by a layer of secretory palisade-like epidermis. Some studies regarding the structure of colleters have focused on secretory cells structure, but not distinguished the secretory and senescent phases. Generally, in mucilage-secreting cells such as colleters, the endoplasmic reticulum and Golgi apparatus are involved in secretion production and transport. In these study, colleters structure of Bathysa gymnocarpa K. Schum. and B. stipulata (Vell.) C. Presl. (Rubiaceae) were determined in two phases: a secretory phase and a senescence one. Samples were collected and processed by usual light and electron microscopy techniques. Studied colleters are constituted by an epidermal palisade layer and a central axis formed by parenchymatic cells with rare vascular traces. During the secretory phase, epidermal cells presented a dense cytoplasm, small vacuoles, enhanced rough and smooth endoplasmic reticulum, and a Golgi apparatus close to large vesicles. During the senescence phase epidermal cells presented a disorganized membrane system. No intact organelles or vesicles were observed. The outer cell wall exhibited similar layers to that observed during the secretory phase. The senescent phase is easily defined by the morphology of the colleters, but not well defined at subcellular level. Our research suggests that programmed cell death starts on secretory phase. However, more evidences are needed to evaluate the phenomena.

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Leaf CO2 assimilation (A) as a function of photosynthetic photon flux density (Q) or intercellular CO2 concentration (Ci) and chlorophyll fluorescence measurements were carried out on four tropical woody species growing in forest gap and understorey (Bauhinia forficata Link. and Guazuma ulmifolia Lam. as pioneers, and Hymenaea courbaril L. and Esenbeckia leiocarpa Engl. as non-pioneers). Chlorophyll fluorescence indicated similar acclimation capacities of photochemical apparatus to contrasting light environments irrespective to plant species. Maximum CO2 assimilation and quantum yield derived from A/Q curves indicated higher photosynthetic capacity in pioneer than in non-pioneer species in forest gap. However, the differences among species did not show a straightforward relation with their successional status regarding data derived from A/Q curves under understorey conditions. Both successional groups are able to sustain positive carbon balance under contrasting natural light availabilities, modifying photochemical and biochemical photosynthetic traits with similar phenotypic plasticity capacity.

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A high-frequency cyclonverter acts as a direct ac-to-ac power converter circuit that does not require a diode bidge rectifier. Bridgeless topology makes it possible to remove forward voltage drop losses that are present in a diode bridge. In addition, the on-state losses can be reduced to 1.5 times the on-state resistance of switches in half-bridge operation of the cycloconverter. A high-frequency cycloconverter is reviewed and the charging effect of the dc-capacitors in ``back-to-back'' or synchronous mode operation operation is analyzed. In addition, a control method is introduced for regulating dc-voltage of the ac-side capacitors in synchronous operation mode. The controller regulates the dc-capacitors and prevents switches from reaching overvoltage level. This can be accomplished by variating phase-shift between the upper and the lower gate signals. By adding phase-shift between the gate signal pairs, the charge stored in the energy storage capacitors can be discharged through the resonant load and substantially, the output resonant current amplitude can be improved. The above goals are analyzed and illustrated with simulation. Theory is supported with practical measurements where the proposed control method is implemented in an FPGA device and tested with a high-frequency cycloconverter using super-junction power MOSFETs as switching devices.

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Gastroesophageal reflux (GER) disorder was studied in children and adolescents with chronic and/or recurrent rhinosinusitis not associated with bronchial asthma. Ten children with a clinical and radiological diagnosis of chronic and/or recurrent rhinosinusitis, consecutively attended at the Pediatric Otolaryngology Outpatient Clinic, Federal University of São Paulo, were evaluated. Prolonged esophageal pH monitoring was used to investigate GER disorder. The mean age of the ten patients evaluated (eight males) was 7.4 ± 2.4 years. Two patients presented vomiting as a clinical manifestation and one patient presented retrosternal pain with a burning sensation. Twenty-four-hour esophageal pH monitoring was performed using the Sandhill apparatus. An antimony probe electrode was placed in the lower third of the esophagus, confirmed by fluoroscopy and later by a chest X-ray. The parameters analyzed by esophageal pH monitoring included: total percent time of the presence of acid esophageal pH, i.e., pH below 4 (<4.2%); total number of acid episodes (<50 episodes); number of reflux episodes longer than 5 min (3 or less), and duration of the longest reflux episode (<9.2 min). One patient (1/10, 10%) presented a 24-h esophageal pH profile compatible with GER disorder. This data suggest that an association between chronic rhinosinusitis not associated with bronchial asthma and GER disorder may exist in children and adolescents, especially in those with compatible GER disorder symptoms. In these cases, 24-h esophageal pH monitoring should be performed before indicating surgery, since the present data suggest that 10% of chronic rhinosinusitis surgeries can be eliminated.

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Desmin is the main intermediate filament (IF) protein of muscle cells. In skeletal muscle, desmin IFs form a scaffold that interconnects the entire contractile apparatus with the subsarcolemmal cytoskeleton and cytoplasmic organelles. The interaction between desmin and the sarcolemma is mediated by a number of membrane proteins, many of which are Ca2+-sensitive. In the present study, we analyzed the effects of the Ca2+ chelator EGTA (1.75 mM) on the expression and distribution of desmin in C2C12 myoblasts grown in culture. We used indirect immunofluorescence microscopy and reverse transcription polymerase chain reaction (RT-PCR) to analyze desmin distribution and expression in C2C12 cells grown in the presence or absence of EGTA. Control C2C12 myoblasts showed a well-spread morphology after a few hours in culture and became bipolar when grown for 24 h in the presence of EGTA. Control C2C12 cells showed a dense network of desmin from the perinuclear region to the cell periphery, whereas EGTA-treated cells showed desmin aggregates in the cytoplasm. RT-PCR analysis revealed a down-regulation of desmin expression in EGTA-treated C2C12 cells compared to untreated cells. The present results suggest that extracellular Ca2+ availability plays a role in the regulation of desmin expression and in the spatial distribution of desmin IFs in myoblasts, and is involved in the generation and maintenance of myoblast cell shape.

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Heart rate variability (HRV) provides important information about cardiac autonomic modulation. Since it is a noninvasive and inexpensive method, HRV has been used to evaluate several parameters of cardiovascular health. However, the internal reproducibility of this method has been challenged in some studies. Our aim was to determine the intra-individual reproducibility of HRV parameters in short-term recordings obtained in supine and orthostatic positions. Electrocardiographic (ECG) recordings were obtained from 30 healthy subjects (20-49 years, 14 men) using a digital apparatus (sampling ratio = 250 Hz). ECG was recorded for 10 min in the supine position and for 10 min in the orthostatic position. The procedure was repeated 2-3 h later. Time and frequency domain analyses were performed. Frequency domain included low (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.4 Hz) bands. Power spectral analysis was performed by the autoregressive method and model order was set at 16. Intra-subject agreement was assessed by linear regression analysis, test of difference in variances and limits of agreement. Most HRV measures (pNN50, RMSSD, LF, HF, and LF/HF ratio) were reproducible independent of body position. Better correlation indexes (r > 0.6) were obtained in the orthostatic position. Bland-Altman plots revealed that most values were inside the agreement limits, indicating concordance between measures. Only SDNN and NNv in the supine position were not reproducible. Our results showed reproducibility of HRV parameters when recorded in the same individual with a short time between two exams. The increased sympathetic activity occurring in the orthostatic position probably facilitates reproducibility of the HRV indexes.

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The present study investigated the effect of thioperamide (THIO), an H3 histaminergic receptor antagonist, microinjected into the cerebellar vermis on emotional memory consolidation in male Swiss albino mice re-exposed to the elevated plus-maze (EPM). We implanted a guide cannula into the cerebellar vermis using stereotactic surgery. On the third day after surgery, we performed behavioral tests for two consecutive days. On the first day (exposure), the mice (n=10/group) were exposed to the EPM and received THIO (0.06, 0.3, or 1.5 ng/0.1 µL) immediately after the end of the session. Twenty-four hours later, the mice were re-exposed to the EPM under the same experimental conditions, but without drug injection. A reduction in the exploration of the open arms upon re-exposure to the EPM (percentage of number of entries and time spent in open arms) compared with the initial exposure was used as an indicator of learning and memory. One-way analysis of variance (ANOVA) followed by the Duncan post hoc test was used to analyze the data. Upon re-exposure, exploratory activity in the open arms was reduced in the control group, and with the two highest THIO doses: 0.3 and 1.5 ng/0.1 µL. No reduction was seen with the lowest THIO dose (0.06 ng/0.1 µL), indicating inhibition of the consolidation of emotional memory. None of the doses interfered with the animals' locomotor activity. We conclude that THIO at the lowest dose (0.06 ng/0.1 µL) microinjected into the cerebellum impaired emotional memory consolidation in mice.

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Smart home implementation in residential buildings promises to optimize energy usage and save significant amount of energy simply due to a better understanding of user's energy usage profile. Apart from the energy optimisation prospects of this technology, it also aims to guarantee occupants significant amount of comfort and remote control over home appliances both at home locations and at remote places. However, smart home investment just like any other kind of investment requires an adequate measurement and justification of the economic gains it could proffer before its realization. These economic gains could differ for different occupants due to their inherent behaviours and tendencies. Thus it is pertinent to investigate the various behaviours and tendencies of occupants in different domain of interests and to measure the value of the energy savings accrued by smart home implementations in these domains of interest in order to justify such economic gains. This thesis investigates two domains of interests (the rented apartment and owned apartment) for primarily two behavioural tendencies (Finland and Germany) obtained from observation and corroborated by conducted interviews to measure the payback time and Return on Investment (ROI) of their smart home implementations. Also, similar measures are obtained for identified Australian use case. The research finding reveals that building automation for the Finnish behavioural tendencies seems to proffers a better ROI and payback time for smart home implementations.

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Electric energy demand has been growing constantly as the global population increases. To avoid electric energy shortage, renewable energy sources and energy conservation are emphasized all over the world. The role of power electronics in energy saving and development of renewable energy systems is significant. Power electronics is applied in wind, solar, fuel cell, and micro turbine energy systems for the energy conversion and control. The use of power electronics introduces an energy saving potential in such applications as motors, lighting, home appliances, and consumer electronics. Despite the advantages of power converters, their penetration into the market requires that they have a set of characteristics such as high reliability and power density, cost effectiveness, and low weight, which are dictated by the emerging applications. In association with the increasing requirements, the design of the power converter is becoming more complicated, and thus, a multidisciplinary approach to the modelling of the converter is required. In this doctoral dissertation, methods and models are developed for the design of a multilevel power converter and the analysis of the related electromagnetic, thermal, and reliability issues. The focus is on the design of the main circuit. The electromagnetic model of the laminated busbar system and the IGBT modules is established with the aim of minimizing the stray inductance of the commutation loops that degrade the converter power capability. The circular busbar system is proposed to achieve equal current sharing among parallel-connected devices and implemented in the non-destructive test set-up. In addition to the electromagnetic model, a thermal model of the laminated busbar system is developed based on a lumped parameter thermal model. The temperature and temperature-dependent power losses of the busbars are estimated by the proposed algorithm. The Joule losses produced by non-sinusoidal currents flowing through the busbars in the converter are estimated taking into account the skin and proximity effects, which have a strong influence on the AC resistance of the busbars. The lifetime estimation algorithm was implemented to investigate the influence of the cooling solution on the reliability of the IGBT modules. As efficient cooling solutions have a low thermal inertia, they cause excessive temperature cycling of the IGBTs. Thus, a reliability analysis is required when selecting the cooling solutions for a particular application. The control of the cooling solution based on the use of a heat flux sensor is proposed to reduce the amplitude of the temperature cycles. The developed methods and models are verified experimentally by a laboratory prototype.