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The endurance of unmanned aerial vehicles (UAVs) is a critical factor in expanding the scope of their applications. Extended flight times enable UAVs to undertake longer missions, cover larger areas and perform tasks such as persistent surveillance, data collection and search and rescue operations. Optimal trajectory planning is a cost-effective method to significantly enhance UAV endurance and performance by minimizing fuel consumption. This study introduces a novel numerical optimization framework to maximize UAV endurance. Specifically, we address the problem of determining optimal thrust and cruise angle of attack for a UAV in 2D space under specific initial, periodic and boundary conditions. By normalizing the free final time optimal control problem and employing Fourier collocation and quadrature, we transform it into a nonlinear programming problem. A key contribution of this work is accurately detecting and reconstructing the thrust history, including jump discontinuities, directly from Fourier pseudospectral data without smoothing techniques. The proposed method outperforms existing approaches in solving the periodic energy-optimal path planning problem for UAVs, as it effectively reconstructs the bang-bang thrust profile, facilitating rapid and efficient thrust adjustments essential for various flight maneuvers. Furthermore, the algorithm aligns with the UAV model, ensuring seamless integration into real-world control systems. The method’s independence from prediction horizon length, due to the use of Fourier collocation on the normalized interval $[0,2\pi ]$, is a notable advantage. This characteristic offers potential for future applications in various fields involving nonsmooth optimal control problems. This research generally provides a valuable tool for researchers and engineers working on UAV design and operation, paving the way for more efficient and effective UAV systems.

This paper describes the recent advancements in the development of nanoelectronic SONOS nonvolatile semiconductor memory (NVSM) devices and technology, which are employed in both embedded applications, such as microcontrollers, and 'stand-alone', high-density, memory applications, such as cell phones and memory 'sticks'. Multi-dielectric devices, such as the MNOS devices, were among the first NVSM; however, over the ensuing years the double polysilicon, floating-gate device has become the dominant semiconductor NVSM technology. Today, however, questions arise as to future scaling and cost effectiveness of floating gate technology – questions, which have sparked renewed interest in SONOS technology. The latter offers a single polysilicon device structure with reduced lithography steps together with compact cell layouts - compatible with 'standard' CMOS technology for cost effectiveness. In addition, SONOS technology offers performance features, such as reduced erase and write voltage levels to ease the design of peripheral memory circuits with a decrease in electric fields and localized charge storage for improved reliability and multi-bit storage, and ease of memory testing. A special feature of SONOS technology is radiation hardness, which makes this technology ideal for advanced Space and Military systems. SONOS devices use ultra-thin tunnel oxides (2nm) and operate with 'modified' Fowler-Nordheim and 'direct' tunneling in both erase and write (program) modes. A thicker tunnel oxide SONOS device (5nm), called the NROM™ device, uses 'hot electron injection for programming and 'hot hole band-to-band tunneling' for erase. The NROM™ device provides spatially isolated, two-bit storage with the possibility of multi-level charge (MLC) storage at each bit location. This paper describes the physical electronics for these device structures and their erase/write, retention and endurance characteristics. In addition, several novel SONOS device structures are discussed as potential candidates for future NVSM.

This paper provides a mathematical description based on the theory of differential equations, for the dynamics of lactate production and removal. Analytical and numerical results for training/exercise of endurance of athletes are presented based on the common concept of training impulse (Trimp). The relationships between activity, production rate, and removal strategies of lactate are studied. Parameters are estimated from published data. A model for optimum removal of lactate after exercise is developed. The model provides realistic predictions when compared with experimental results. We show some specific examples for the usefulness of the mathematical model by studying some recent problems discussed in the literature. (a) Is interval exercise more beneficial than steady-state exercise? (b) What is the optimum aerobic power during recovery? We discuss whether steady-state exercise gives higher Trimp than interval exercise, when imposing an upper boundary for the lactate concentration as a constraint. The model allows for testing all imaginable kinds of steady-state and interval exercises in search of the optimal exercise regime for individuals with various kinds of characteristics. In general, the dynamic model constitute a powerful tool describing the processes by which the concentration of lactate can be studied and controlled to decrease fatigue and increase endurance.

We deal with the endurance problem of Phase Change Memories (PCM) by proposing Compression for Endurance in PCM RAM$($CEPRAM$)$, a technique to elongate the lifespan of PCM-based main memory through compression. We introduce a total of three compression schemes based on already existent schemes, but targeting compression for PCM-based systems. We do a two-level evaluation. First, we quantify the performance of the compression, in terms of compressed size, bit-flips and how they are affected by errors. Next, we simulate these parameters in a statistical simulator to study how they affect the endurance of the system. Our simulation results reveal that our technique, which is built on top of Error Correcting Pointers (ECP) but using a high-performance cache-oriented compression algorithm modified to better suit our purpose, manages to further extend the lifetime of the memory system. In particular, it guarantees that at least half of the physical pages are in usable condition for 25% longer than ECP, which is slightly more than 5% more than a scheme that can correct 16 failures per block.

In order to ascertain the utility of a 250 Hz NSD Powerball^® gyroscope in increasing the maximum grip force and muscular endurance of the forearm, ten adults without pathology in their upper limbs exercised one forearm with the device during a period of one month. We evaluated grip strength and forearm muscle endurance with a Jamar dynamometer both at the end of the month as well as after a resting period of one month. There was a tendency (not statistically significant p = 0.054), for the volunteers to increase their maximum grip strength. There was also highly significant increase in muscle endurance (p = 0.00001), a gain that remained slightly unchanged after the rest. Because the gyroscope generates random multidirectional forces to the forearm, the reactive muscle contraction is likely to stimulate more efficient neuromuscular contro of the wrist, a conclusion which our work appears to validate. The use of Powerball^® in forearm proprioception deficient patients is, therefore, justified.

Purpose: Back muscles' endurance assessment provides an objective indicator of the functional capacity of the back. This study sought to establish a gender and age referenced normative data for back muscles endurance for a Sub-Saharan African population. Methods: This cross sectional study involved 1253 (623 male, 630 female) consecutive participants between the ages of 11 and 69 years without a history of symptomatic LBP within one year to the time of the study. Participants were recruited from eight secondary schools, two universities and two teaching hospitals, respectively. All participants underwent assessment of the back extensor muscles' endurance using the modified Biering-Sorensen test of muscular endurance. The mean and percentile data for endurance time were determined for six gender/age groups classified on a range of 10 years. Results: The mean endurance time (ET) of all the participants was 119 ± 53.6 secs. Men exhibited a significantly (p = 0.001) higher ET than women (125.9 ± 53.3 versus 112.6 ± 53.1 secs). Using percentile values cut-points; poor endurance (less than 25th), moderate endurance (25–75th) and good endurance (> 75th percentile) were < 85.0 secs, 85–163 secs, and > 163 secs, respectively for male; and < 69.8 secs, 69.8–148 secs and > 148 secs, respectively for female. Conclusion: The normative values derived in this study would be useful in assessing impairment in back muscles' endurance in both healthy and patient populations. The results suggest that age, gender and anthropometric factors can significantly influence back muscles' endurance.

Purpose: This study aims to determine the relation among the commonly used different tests of evaluating core stability performance. Establishing this relationship is important as different authors have used different types of tests for evaluating core stabilization in their study yet relation among these tests and the individual importance of each of these tests is not clearly established so far. Methods: Among 40 recreationally active subjects the core stability performance was evaluated using variety of different tests reported in the previous literatures. Results: Results show that there was no significant correlation among the performance scores on different test of core stability. Conclusions: The assessment of the core stability performance must be in concordance with the need of the individual and of the study. Also, different tasks or sports selectively require different components of the core stability. In order to evaluate more than one component of the core stability performance, the different combinations of the tests must be used. If one wishes to test all the components of the core stabilization, then no single test is sufficient and a battery of test must be used to assess different components separately.

Reduced shoulder endurance in rotator cuff tear patients has been observed clinically. A simple and inexpensive shoulder endurance test protocol was developed. This study reports the test-retest reliability of the protocol. Twenty healthy volunteers without a history of shoulder pathology participated in the study. Each subject was tested twice, each on a separate day. Test-retest correlation coefficients of the arm endurance times were 0.59 and 0.60 for the dominant and nondominant sides, respectively. The protocol appears promising for assessing shoulder function.

Background: Older individuals face a high risk of mobility and body composition decline, which can affect their independence. In light of a current uncertain healthcare situation created by the coronavirus (COVID-19) pandemic, healthcare paradigm has been shifted with increased demand for a practical measure to promote standard home healthcare services for all individuals, including older adults.

Objective: This study explored the feasibility and validity of seated push-up tests (SPUTs) as clinical measures to reflect the body composition, muscle strength, and mobility among community-dwelling older individuals, aged $\ge 65$ years ($n=82$).

Methods: Participants were cross-sectionally assessed using SPUTs with various demanding forms, including the 1-time SPUT (1SPUT) along with its upper limb loading SPUT (ULL-SPUT), 5-time SPUT (5SPUT), 10-time SPUT (10SPUT), and 1-min SPUT (1minSPUT) and standard measures.

Results: Participants who passed and failed a 1SPUT showed significant differences in the outcomes of all standard measures ($p<0.05$). The ULL-SPUT significantly correlated to all body composition, muscle strength, and mobility ($r=0.247$–0.785; $p<0.05$). Outcomes of 1minSPUT significantly correlated with muscle strength and mobility outcomes ($r=0.306$–0.526; $p<0.05$). Participants reported no adverse effects following the SPUTs.

Conclusion: The findings suggest the use of the 1SPUT, ULL-SPUT, and 1minSPUT as practical measures to reflect the body composition, muscle strength, and mobility of older individuals, according to their functional levels. The tests may especially clinically benefit those with lower limb limitations and those in settings with limited space and equipment.

In this work, a resistive switching memory device was fabricated based on egg protein, a natural biomaterial. The effect of graphene composite on the resistive switching characteristics of the device was investigated. The experimental results show that both pure egg protein and graphene composite devices exhibit bipolar nonvolatile resistive conversion properties. Both devices have good data retention capability. Furthermore, the composite of graphene can effectively improve the device endurance and the consistency of the on-state current distribution of the device. Based on the theory of capture and de-capture of charge carrier, the mechanism of resistive switching is analyzed.

Difficulties in the fabrication of direct interface of ferroelectric BiFeO₃ on the gate of ferroelectric field effect transistor (FeFET) is well known. This paper reports the optimization and fabrication of ferroelectric/dielectric (BiFeO₃/HfO${}_2)$ gate stack for the FeFET applications. RF magnetron sputtering has been used for the deposition of BiFeO₃, HfO₂ films and their stack. X-Ray diffraction (XRD) analysis of BiFeO₃ shows the dominant perovskite phase of (104), (110) orientation at 2$\theta =32^{\circ }$ at the annealing temperature of 500${}^{\circ }$C. XRD analysis also confirms the amorphous nature of the HfO₂ film at annealing temperature of 400${}^{\circ }$C, 500${}^{\circ }$C and 600${}^{\circ }$C. Multiple angle analysis shows the variation ion the refractive index between 2.98–3.0214 for BiFeO₃ and 2.74–2.9 for the HfO₂ film with the annealing temperature. Metal/Ferroelectric/Silicon (MFS), Metal/Ferroelectric/Metal (MFM), Metal/Insulator/Silicon (MIS), and Metal/Ferroelectric/Insulator/Silicon (MFIS) structures have been fabricated to obtain the electric characteristic of the ferroelectric, dielectric and their stacks. Electrical characteristics of the MFIS structure show the memory improvement from 2.7V for MFS structure to 4.65V for MFIS structure with 8nm of buffer dielectric layer. This structure also shows the breakdown voltage of 40V with data retention capacity greater than $9\times 10^9$ iteration cycles.

The flight conditions, small length scale, and low altitude flight of mini-UAVs lend them to the low Reynolds number of less than 300,000 in which the aircraft performance is significantly degraded. In such operating conditions, the aerodynamic performance of aircraft is critically dependent on its lifting surface which is the wing configuration and high-cambered airfoils are equipped to generate enough lift to keep the aircraft and its payload airborne at low operating speeds. However, the aerodynamic performance of airfoils at low Reynolds number is significantly degraded due to the early separation of flow. This results in higher form of drag and lower lift which leads to higher power required to generate thrust for the aircraft to overcome drag and remain airborne. Consequently, the range and endurance are significantly reduced. This paper investigates the interactive effects of different Alula deflection angles and span ratios on the aerodynamic efficiency of a three-dimensional (finite) swept back wing during cruise flight. A total of nine wing configurations are designed with different Alula deflection angles (4°, 13°, and 22°) and span ratios (5%, 10%, and 15%). Investigations are carried out using numerical simulations and wind tunnel experiments. Overall, an enhanced aerodynamic efficiency is achieved for wings equipped with Alula configuration at 13° deflection angle and 15% span ratio as well as 22° deflection angle and 5% span ratio, and they have 9.3% and 4.5% higher aerodynamic efficiency compared to the clean wing. The endurance of electric-powered mini-UAVs is exponentially proportional to aerodynamic efficiency. Hence, the resulting wing configurations from this research with improved aerodynamic efficiency have a promising effect on the endurance enhancement of UAVs during the cruise envelope of flight.

Background: Smoking has a number of well-documented negative effects on health. The seemingly common knowledge is that smoking causes low back pain. Cigarette smoking is associated with poor physical fitness and reduced muscle strength.¹ The specific effects of smoking on the efficacy of the lumbar extensors have been previously investigated where individuals with chronic low back pain often have weaker lumbar extensor muscles.² Rigorous exercises, however, reverse this weakness.

Hypothesis: This study hypothesizes that cigarette smoking is associated with deficits in the lumbar extensor strength that make the back susceptible to mechanical stress and injury.

Study Design: Cohort study.

Methods: The objective of this study was to determine the isometric lumbar extensor strength before and after fatigue challenge amongst smokers and nonsmokers. A pre-test and post-test design was used to determine the differences in the lumbar extensor endurance between smokers and nonsmokers.

Results: The result of the study confirms a relationship between reduced lumbar extensor strength and cigarette smoking. The negative impact of smoking on lumbar extensors suggests increased susceptibility to lumbar injuries and thereby low back pain.

Conclusions: Smokers demonstrated reduced muscle strength and fatigability of the lumbar extensors and they may perhaps be vulnerable to lumbar spine injuries. The study also confirmed that spinal extension exercises increased the endurance time of the lumbar extensor muscles.

This paper describes the recent advancements in the development of nanoelectronic SONOS nonvolatile semiconductor memory (NVSM) devices and technology, which are employed in both embedded applications, such as microcontrollers, and 'stand-alone', high-density, memory applications, such as cell phones and memory 'sticks'. Multi-dielectric devices, such as the MNOS devices, were among the first NVSM; however, over the ensuing years the double polysilicon, floating-gate device has become the dominant semiconductor NVSM technology. Today, however, questions arise as to future scaling and cost effectiveness of floating gate technology – questions, which have sparked renewed interest in SONOS technology. The latter offers a single polysilicon device structure with reduced lithography steps together with compact cell layouts - compatible with 'standard' CMOS technology for cost effectiveness. In addition, SONOS technology offers performance features, such as reduced erase and write voltage levels to ease the design of peripheral memory circuits with a decrease in electric fields and localized charge storage for improved reliability and multi-bit storage, and ease of memory testing. A special feature of SONOS technology is radiation hardness, which makes this technology ideal for advanced Space and Military systems. SONOS devices use ultra-thin tunnel oxides (2nm) and operate with 'modified' Fowler-Nordheim and 'direct' tunneling in both erase and write (program) modes. A thicker tunnel oxide SONOS device (5nm), called the NROM™ device, uses 'hot electron injection for programming and 'hot hole band-to-band tunneling' for erase. The NROM™ device provides spatially isolated, two-bit storage with the possibility of multi-level charge (MLC) storage at each bit location. This paper describes the physical electronics for these device structures and their erase/write, retention and endurance characteristics. In addition, several novel SONOS device structures are discussed as potential candidates for future NVSM.