A vector light sensor for 3D proximity applications: Designs, materials, and applications

In this thesis, a three-dimensional design of a vector light sensor for angular proximity detection applications is realized. 3D printed mesa pyramid designs, along with commercial photodiodes, were used as a prototype for the experimental verification of single-pixel and two-pixel systems. The operation principles, microfabrication details, and experimental verification of micro-sized mesa and CMOS-compatible inverse vector light pixels in silicon are presented, where p-n junctions are created on pyramid’s facets as photodiodes. The one-pixel system allows for angular estimations, providing spatial proximity of incident light in 2D and 3D. A two-pixel system was further demonstrated to have a wider-angle detection. Multilayered carbon nanotubes, graphene, and vanadium oxide thin films as well as carbon nanoparticles-based composites were studied along with cost effective deposition processes to incorporate these films onto 3D mesa structures. Combining such design and materials optimizations produces sensors with a unique design, simple fabrication process, and readout integrated circuits’ compatibility. Finally, an approach to utilize such sensors in smart energy system applications as solar trackers, for automated power generation optimizations, is explored. However, integration optimizations in complementary-Si PV solar modules were first required. In this multi-step approach, custom composite materials are utilized to significantly enhance the reliability in bifacial silicon PV solar modules. Thermal measurements and process optimizations in the development of imec’s novel interconnection technology in solar applications are discussed. The interconnection technology is used to improve solar modules’ performance and enhance the connectivity between modules’ cells and components. This essential precursor allows for the effective powering and consistent operations of standalone module-associated components, such as the solar tracker and Internet of Things sensing devices, typically used in remote monitoring of modules’ performance or smart energy systems. Such integrations and optimizations in the interconnection technology improve solar modules’ performance and reliability, while further reducing materials and production costs. Such advantages further promote solar (Si) PV as a continuously evolving renewable energy source that is compatible with new waves of smart city technology and systems

Circadian Modulation Of Breathing Stability And Respiratory Plasticity

Purpose: Our project was designed to determine the effect of time of day on multiple mechanisms influencing breathing stability and respiratory plasticity. We investigated if the number and duration of breathing events coupled to upper airway collapsibility, as well as the carbon dioxide reserve, chemoreflex sensitivity and arousal threshold during non-rapid eye movement (NREM) sleep were affected by the time of day. In addition, we examined if mild intermittent hypoxia (IH) initiates long-term facilitation of upper airway muscle activity leading to a reduction in the therapeutic continuous positive airway pressure required to eliminate breathing events. Methods: Male participants with obstructive sleep apnea completed a constant routine protocol that consisted of sleep sessions in the evening (10 PM to 1 AM), morning (6 AM to 9 AM), and afternoon (2 PM to 5 PM). On one occasion the number and duration of breathing events was ascertained for each sleep session. For breathing events detected during these sessions the rate of change of respiratory effort, maximum respiratory effort immediately prior to termination of an event, and the maximum tidal volume and the minimum partial pressure of end-tidal carbon dioxide (PETCO2) immediately following an event were measured Participants then completed the same protocol on two additional occasions, where the critical closing pressure that demarcated upper airway collapsibility was determined on one, and baseline levels of carbon dioxide PET(CO2) and minute ventilation, as well as the PET(CO2) that demarcated the apneic threshold and hypocapnic ventilatory response were measured on the other (the order of these 2 visits was randomized). In the second aim of the study, male participants with obstructive sleep apnea were treated with twelve 2-minute episodes of hypoxia (PETO2 ≈ 50 mmHg) separated by 2-minute intervals of normoxia in the presence of PETCO2 that was sustained 3 mmHg above baseline. During recovery from the last episode the positive airway pressure was reduced in a step-wise fashion until flow limitation was evident. The participants also completed a sham protocol under normocapnic conditions, which mimicked the timeframe of the IH protocol. Results: The duration of breathing events was consistently greater in the morning compared with the evening and afternoon during N1 and N2, while an increase in event frequency was evident during N1. The critical closing pressure was increased in the morning (2.68 ± 0.98 cmH2O) compared with the evening (1.29 ± 0.91 cmH2O; P ≤ 0.02) and afternoon (1.25 ± 0.79; P ≤ 0.01). The increase in the critical closing pressure was correlated to the decrease in the baseline partial pressure of carbon dioxide in the morning compared with the afternoon and evening (r = −0.73, P ≤ 0.005).. The nadir of core body temperature during sleep occurred in the morning and was accompanied by reductions in minute ventilation and PETCO2 compared with the evening and afternoon (minute ventilation: 5.3 ± 0.3 vs. 6.2 ± 0.2 vs. 6.1 ± 0.2 l/min, P lt; 0.02; PET(CO2): 39.7 ± 0.4 vs. 41.4 ± 0.6 vs. 40.4 ± 0.6 Torr, P \u3c 0.02). The carbon dioxide reserve was reduced, and the hypocapnic ventilatory response increased in the morning compared with the evening and afternoon (carbon dioxide reserve: 2.1 ± 0.3 vs. 3.6 ± 0.5 vs. 3.5 ± 0.3 Torr, P \u3c 0.002; hypocapnic ventilatory response: 2.3 ± 0.3 vs. 1.6 ± 0.2 vs. 1.8 ± 0.2 l·min(-1)·mmHg(-1), P \u3c 0.001). The rate of change of respiratory effort was similar in N2 compared to N1 but the maximum respiratory effort immediately prior to event termination was greater (-10.7 ± 1.2 vs. -9.6 ± 1.0 cmH2O/s, P \u3c 0.05). Likewise, tidal volume was increased (1169 ± 105 vs. 1082 ± 100 ml, P \u3c 0.05) and PETCO2 was decreased (37.0 ± 0.8 vs. 37.7 ± 0.8 mmHg P \u3c 0.05) following events in N2 compared to N1. A similar tidal volume and PETCO2 response was evident following events in the morning compared to the evening independent of sleep stage. After exposure to IH the therapeutic pressure was significantly reduced (Δ CPAP = - 4.95 ± 0.5 cmH2O, p \u3c 0.001) without evidence of flow limitation (P \u3e 0.2) or increases in upper airway resistance (P \u3e 0.4). In contrast, a similar decrease in pressure was accompanied by significant flow limitation (P \u3c 0.003) and an increase in upper airway resistance (P \u3c 0.01) following completion of the sham protocol. Conclusion: Our findings indicate that time of day affects the duration and frequency of events, coupled with alterations in upper airway collapsibility and chemoreflex properties during sleep, which may contribute to increases in breathing instability in the morning compared with other periods throughout the day/night cycle in individuals with sleep apnea. We propose that increases in airway collapsibility in the morning may be linked to an endogenous modulation of baseline carbon dioxide levels and chemoreflex sensitivity, which are independent of the consequences of sleep apnea. We also conclude that alterations in the arousal threshold, reflected by an increase in respiratory effort at event termination, coupled to increases in tidal volume and reductions in PETCO2 contribute to modifications in event duration and frequency associated with variations in sleep state or time of night. In addition, Exposure to IH decreases the therapeutic pressure required to eliminate apneic events which could improve treatment compliance. This possibility coupled with the direct beneficial effects of IH on co-morbidities linked to sleep apnea suggests that IH may have a multipronged therapeutic effect on sleep apnea

Saving the Sustainability of the European Union, Fighting Terrorism

Albeit the absence of an agreement on the definition, terrorism as studied in this literature has a complex nature and diverse factors that are involved. Furthermore, dealing with terrorism has become the centrepiece of foreign policies of many countries worldwide. The European Union has a long history of fighting terrorism. Yet, the current terrorism threats have shaken the bases of the Union. According to the authors’ assessment and evaluation, terrorism in Europe, in the aftermath of the Second World War, occurs due to the unsustainable foreign policies of the EU member states. To save the European Union and to fight terrorism, the authors suggest a framework based on four complementary headlines: i) Education, ii) Social justice and human rights, iii) Law enforcement, and iv) Sustainable common defence policy. A prerequisite to the success of this framework is a revision of the Europe-transatlantic relations to address the imbalance in the EU relations with USA

The economics of irrigating wheat in a humid climate - A study in the East of England

In the UK, wheat is the most important cultivated cereal, grown extensively as a rainfed crop. Irrigation of wheat has previously been considered uneconomic, but increases in world wheat prices and recent droughts have led to some farmers revising their views. Widespread adoption of wheat irrigation would have major implications for wheat production, the irrigation industry and water resources in regions that are already water scarce. This study investigated the financial viability of irrigating winter wheat grown on a sandy loam soil in the East of England. Long-term climate data (1961–2011) for Silsoe (Bedfordshire) was used to drive a biophysical crop model to assess irrigation water requirements and yield response. Modelling assumed a typical irrigation schedule to maximise yield and quality, and average reported wheat prices for 2007 to 2012. Irrigation costs were calculated assuming an overhead mobile hosereel–raingun system applying river water, abstracted either in summer and used directly, or abstracted in winter and stored in an on-farm reservoir. The results suggest that the yield benefit would justify supplemental irrigation by farmers who have unused irrigation equipment and unused summer water, although irrigation of higher-value field vegetable crops later in the season would normally take precedence – the Added Value of Water (AVW) usefully applied to milling winter wheat under these conditions ranged between 0.24 and 0.32 £ m−3. Investment in new irrigation schemes could also be marginally viable if unused summer river water was available for direct abstraction (AVW = 0.08 £ m−3). Investments in new farm reservoirs for irrigating wheat are currently not profitable (AVW = –0.23 £ m−3). Sensitivity analysis suggests that in the longer term, the expected increase in world wheat prices and the impacts of climate change are likely to make the financial benefits stronger, particularly in the drier catchments further east and on low moisture retentive soils, but competing demands for water would still make extensive wheat irrigation unlikely

New eigenvalue estimates involving Bessel functions

Given a compact Riemannian manifold (M n , g) with boundary ∂M , we give an estimate for the quotient ∂M f dµ g M f dµ g , where f is a smooth positive function defined on M that satisfies some inequality involving the scalar Laplacian. By the mean value lemma established in [37], we provide a differential inequality for f which, under some curvature assumptions, can be interpreted in terms of Bessel functions. As an application of our main result, a direct proof is given of the Faber-Krahn inequalities for Dirichlet and Robin Laplacian. Also, a new estimate is established for the eigenvalues of the Dirac operator that involves a positive root of Bessel function besides the scalar curvature. Independently, we extend the Robin Laplacian on functions to differential forms. We prove that this natural extension defines a self-adjoint and elliptic operator whose spectrum is discrete and consists of positive real eigenvalues. In particular, we characterize its first eigenvalue and provide a lower bound of it in terms of Bessel functions