Tunable Versatile High Input Impedance Voltage-Mode Universal Biquadratic Filter Based on DDCCs

A high input impedance voltage-mode universal biquadratic filter with three input terminals and seven output terminals is presented. The proposed circuit uses three differential difference current conveyors (DDCCs), four resistors and two grounded capacitors. The proposed circuit can realize all the standard filter functions, namely, lowpass, bandpass, highpass, notch and allpass, simultaneously. The proposed circuit offers the features of high input impedance, using only grounded capacitors, and orthogonal controllability of resonance angular frequency and quality factor

Development of Industrial n-PERT Rear Junction Solar Cells with Screen-Printed Aluminum Point Contacts

This work is mainly focused on the development of industrial n-PERT-RJ solar cells with screen-printed Al point contact. In Chapter 1, the global market of photovoltaics and the cell technology of the crystalline silicon photovoltaics were introduced. Silicon transportation during the alloying process of the screen-printed Al point contact formation was investigated in Chapter 2 revealing that is severely affected by the amount of Si-add in the Al paste. The uniform distribution of the Si-add in the Al paste effectively suppressed the outdiffusion of bulk-Si during heating up of the firing process, resulting in a higher passivated area ratio (from 94.1 to 98.7%) of the solar cell’s rear side. The longer recrystallization period during the cooling down procedure of firing process, increased the thickness of the Al-doped p+ region (from 0 to a maximum of 4 μm) underneath the point contact, and supplied a better electrical shielding and a lower J0, Met (Al) (decreasing from 2800 to 635 fA/cm2). The proposed Si transportation model can be supported by the analysis of contact microstructures and VOC of solar cell devices (increasing from 560 to 682 mV). The SAM results were shown in Chapter 3 to reveal that no voids were formed under the Al point contacts and that the quality of the Al point contacts was highly improved when having Si-add in the Al paste. The feasibility of screen-printed Al point contact was proven. The discussions of the adverse impacts or sacrifices on JSC and FF of the n-PERT-RJ solar cells caused by the Si-add in the Al paste were followed up. The rear side reflectance has a direct impact on JSC, but it was not affected by any amounts of Si-add in the Al paste, merely directly related to the rear-side reflector covered area ratio, so there was no JSC loss caused by the Si-add. The RS increases when the amount of Si-add in the Al paste is increased, but the major increment didn’t come from the decreasing conductivity of the Al metal layer. Rather, most of the increase is caused by the formation of smaller Al point contacts. With the premise of identical contact characteristics, there was a 0.4% FF loss for the n-PERT-RJ solar cells processed with high wt% Si-add Al 7.1 Summary Page 92 paste, compared to those that were metallized with low wt% Si-add Al paste. Because of better contact shielding, a better pFF value was acquired, compensating the higher FF loss. There were two strategies for the [Si] gradient management: (1) increasing the Si-add in Al paste or (2) decreasing the Al matrix above each LCO (decreasing the LCO pitch). The second part of Chapter 3 showed that the contact width and J0, Met (Al) became gradually independent of the LCO pitch when the amount of the Si-add in the Al paste was modified from none to high wt%. In other words, Si-add dominated the effect of suppressing the outdiffusion of bulk-Si. Hence, a “point-line” contact concept was proposed for the rear side, consisting of a dot-shaped LCO and Al finger grid design metallized with high wt% Si-add Al paste. The concept not only maintained the VOC (693 mV) but had 60% bifaciality, providing an additional bifacial gain which further reduces the levelized cost of electricity (LCOE). The n-PERT-RJ solar cell concept plays a bridging role not only on the material switching from p-type to n-type, but also assists migrating from the traditional mc-BSF to the future advanced solar cell concepts (e.g., IBC or tandem). Many optimizations were shown in Chapter 4 for improving solar cell efficiency: (1) a shallower FSF doping profile, which made a better blue response, yielding a 0.3 mA/cm2 JSC gain and a J0, FSF decrease from 30 to 25 fA/cm2; (2) changing to fine-line printing (finger width reducing from 60 to 40 μm) and applying the dash contact concept reduced the effective metal fraction from 3% to 1% resulting in the area-weighted J0, Met (Ag) decreasing from 37.2 to 12 fA/cm2, which brought a 6 mV VOC gain; (3) screen-printed Al point contacts applied on the rear side with 635 mA/cm2 J0, Met (Al) and 1% effective Al contact area fraction made area-weighted J0, Met (Al) reduce more than 80% to 8.3 fA/cm2. The J0, Total was 77.8 fA/cm2 which translated to a VOC of 693 mV and 22.2% cell efficiency. In addition to the device performance improvements, the detailed loss analysis and the potential performance for the n-PERT-RJ solar cells were performed by Quokka3 simulation in the second part of Chapter 4. The efficiency losses from different mechanisms are shown in the free energy loss analysis (FELA); the recombination loss in the FSF and resistive loss in Thesis summary and outlook Page 93 the bulk were the largest two of all loss mechanisms which should be optimized as a higher priority. The roadmap for reaching 700 mV VOC and beyond 23% cell efficiency with diffused surfaces and all screen-printed metallization was also shown. In Chapter 5, a more detailed discussion on the device level was proved. First, it was explained why the selective doping FSF structure had less benefit on our solar cells, only increasing the complexity and cost of the process. Then, the impact of different n-bulk parameters on n-PERT-RJ solar cell performance was revealed. The Rbulk between 1-13 Ω·cm can keep a stable solar cell efficiency. τbulk should be higher than 2 ms preventing severe performance decreases. Reducing the bulk thickness to 145 μm can compensate for the higher cost of the n-type wafers. The n-PERT-RJ solar cells in this thesis perform as well as the advanced passivating contact solar cells today. Only standard mass-production tools were used and the COO is comparable to the p-PERC solar cells with the selective emitter (SE). There was nearly no LeTID degradation, which makes these n-PERT-RJ solar cells have high performance, low cost, simple process, and long-term stability. The result of detailed comparisons of the microstructures, the contact electrical properties and the device performance between PVD-Al and SP-Al rear point contact n-PERT-RJ solar cells were shown in Chapter 6. The SP-Al point contact brought better performance than the PVD-Al point contact, not merely in regards to the electrical properties (J0, Met (Al) of 635 fA/cm2 comparing to 1450 fA/cm2) of the contact, but also to the solar cell efficiency (0.3 % higher). Integrating low (e.g. PVD-Al) and high (e.g. SP-Ag) thermal budget metallization is a challenge. In contrast, the rear SP-Al contacts can co-fire with the front SP-Ag, which is easier to realize using existing solar cell production lines. When discussing the further “bifacial” application on the n-PERT-RJ solar cells and the interconnections on the solar modules, the PVDAl metallization will face more challenges

Extract coefficients of thermal expansion of TaN thin film by tuning the N2 gas flow in the PVD process

Coefficients of thermal expansion (CTE) mismatch between different materials is an essential and critical concern in semiconductor development. During the manufacturing processes, the thermal budget will induce residual stress, occurring the deformation of the material. In the worst case, the thin film or the elements would be broken or failed. [1] However, these mechanical properties are difficult to determine and measure. In this study, we used the simple micro-cantilever beams array as the test key which was fabricated by the MEMS process. We deposited the TaN thin film on the different length cantilevers and then exploited the double layer method and Stoney equation to analyze its mechanical properties [2] [3]. Figure 1 shows the micrograph of the SiO2 cantilever beam deposited with TaN thin film and whose geometry size is also measured by the SEM system. Please click Download on the upper right corner to see the full abstract

Understanding Children’s Travel Experiences via the Drawings

Previous studies primarily focused on the perspective of parents, giving little attention to the viewpoint of children. Exploring children\u27s travel experiences can be challenging both ethically and in terms of data collection. This study overcomes these difficulties by using children\u27s paintings as the method of data collection, which provides objective and measurable data. This study applied means-end chain (MEC) and content analysis to analyze the pictures. A total of 309 pictures were collected, and 13 Attributes(A), 11 Consequences(C), and 7 values(V) of children\u27s travel experience were identified through MEC. Results revealed that children place great value on participating in activities with their families, particularly those that provide joy, happiness, and hedonic value, such as theme parks, natural scenery, and cultural experiences. Therefore, future travel itineraries should include a variety of fun activities for kids to enhance the family travel experience

Indigenous lands and health access:The influence of a sense of place on disparities in post-stroke recovery in Taiwan

Despite many countries having policies and systems for universal healthcare coverage, health disparity persists, with significant variations in disease prevalence and life expectancy between different groups of people. This focused ethnography explored the post-stroke recovery of Indigenous and non-Indigenous populations in three geographical areas in Taiwan. Forty-eight observations and 24 interviews were carried out with 12 dyads of stroke survivors and family caregivers, revealing their varied experiences of healthcare. Findings indicate that repeatedly engaging in social activities in the same place increases stroke survivors' attachment to the environment, facilitating their reintegration into the community and improving wellbeing following stroke. The significance of ‘place’ in post-stroke life and healthcare access is particularly salient for Indigenous people's recovery. Indigenous people tend to employ cultural symbols, such as Indigenous languages and kinship ties, to define and interpret their surrounding environment and identity. Indigenous people residing within or close to their own native communities make better recoveries than those based in urban settings, who are attached to and yet located away from their native lands. A sense of place contributes to identity, while loss of it leads to invisibility and healthcare inaccessibility. To promote equitable healthcare access, future policymaking and care practices should address the environmental and cultural geography and structural barriers that impede the connection between minority groups and the mainstream community healthcare system. The study findings suggest extending welfare resources beyond Indigenous administrative regions and establishing partnerships between Indigenous organisations and the mainstream healthcare system. Leveraging Indigenous people's attachment to cultural symbols and increasing healthcare facilities staffed with Indigenous healthcare workers could help ease structural barriers, maintain identifiable Indigenous beneficiaries and increase entry points into the mainstream healthcare system.</p

Biographical continuation:Recovery of stroke survivors and their family caregivers in Taiwan

AIM: To explore the experiences pertaining to long-term care services from the perspectives of dyads of stroke survivors and their family caregivers in indigenous and non-indigenous communities. BACKGROUND: Stroke occurrence is a life-changing event associated with quality of life for stroke survivors and their families, especially those who provide primary support. Indigenous people are more likely to experience a stroke at a younger age and have a higher likelihood of hospitalisation and death due to health disparities. Few studies have investigated family dyads or indigenous populations to understand their experiences of coping with changed body-self and to contextualise their reintegration into communities post-stroke. METHODS: Ethnographic fieldwork over nine months in 2018-2019 with indigenous, urban-based, and non-indigenous populations, resulting in 48 observations and 24 interviews with 12 dyads in three geo-administrative communities. FINDINGS: The post-stroke recovery trajectory is illuminated, delineating the dyads' life transitions from biographical disruption to biographical continuation. The trajectory is shaped by seven states involving four mindsets and three status passages. The four mindsets are sense of loss and worry, sense of interdependence, sense of independence, and wellbeing state. The status passages identified in this study are acceptance, alteration, and identification. A community-based and family-centred long-term care system, aligning with medical healthcare and community resources, underpinned each dyad's biographical continuation by: (1) providing rehabilitation that afforded time and space for recovery adaptation; (2) acknowledging the individuality of family caregivers and helping to alleviate their multitasking; and (3) reintegrating stroke survivors into their communities. Key to determining the quality of recovery for the indigenous participants was their reintegration into their native community and regaining of identity. Therefore, integrating post-stroke care into various care contexts and incorporating indigenous-specific needs into policymaking can support dyads in adapting to their communities.</p

Motor neuron-derived Thsd7a is essential for zebrafish vascular development via the Notch-dll4 signaling pathway.

BackgroundDevelopment of neural and vascular systems displays astonishing similarities among vertebrates. This parallelism is under a precise control of complex guidance signals and neurovascular interactions. Previously, our group identified a highly conserved neural protein called thrombospondin type I domain containing 7A (THSD7A). Soluble THSD7A promoted and guided endothelial cell migration, tube formation and sprouting. In addition, we showed that thsd7a could be detected in the nervous system and was required for intersegmental vessels (ISV) patterning during zebrafish development. However, the exact origin of THSD7A and its effect on neurovascular interaction remains unclear.ResultsIn this study, we discovered that zebrafish thsd7a was expressed in the primary motor neurons. Knockdown of Thsd7a disrupted normal primary motor neuron formation and ISV sprouting in the Tg(kdr:EGFP/mnx1:TagRFP) double transgenic zebrafish. Interestingly, we found that Thsd7a morphants displayed distinct phenotypes that are very similar to the loss of Notch-delta like 4 (dll4) signaling. Transcript profiling further revealed that expression levels of notch1b and its downstream targets, vegfr2/3 and nrarpb, were down-regulated in the Thsd7a morphants. These data supported that zebrafish Thsd7a could regulate angiogenic sprouting via Notch-dll4 signaling during development.ConclusionsOur results suggested that motor neuron-derived Thsd7a plays a significant role in neurovascular interactions. Thsd7a could regulate ISV angiogenesis via Notch-dll4 signaling. Thus, Thsd7a is a potent angioneurin involved in the development of both neural and vascular systems