Disturbance Frequency Research Articles

Failure and acoustic behavior of combinational flaws sandstone subjected to dynamic compression loads

This paper described work initiated with two objectives in mind. First was to explore the influence of strain rate effects on the strength law and deformation characteristics of plate sandstone with combined flaws. Second objective was to analyze the breaking response law and acoustic behavior of flawed sandstone under the influence of disturbance frequency and prefabricated dip angle. Thus, a self-developed physical simulation test system combined with the real-time AE monitoring system, were conducted a series of dynamic cyclic loading tests on the flawed plate sandstone. The results indicated that the dynamic frequencies and dip angles had significant effects on the deformation, strength and failure mode of specimens. Additionally, the degree of specimen failure decreased with the increase of disturbance frequency under the same inclination angle; along with, the most severe failure occurred when the inclination angle was 45 ° under the same disturbance frequency. The main failure mode of specimens was shear failure from the distribution of AF-RA. Meanwhile, for specimens with small angles (30 °, 45 °) and low frequencies (0.1, 0.3 Hz), the failure types were more complex (tensile-shear mixed failure). On the other hand, the AE characteristics mainly included three stages: I-initial cycle, II-stable development, and III-damage & failure. The CNT and ENE were greatly influenced by the disturbance frequency and inclination angle. In addition, the b-value decreased and fluctuates violently, and the strength of the samples was reduced as the loading frequency decreased. The specimens with smaller inclination angles had larger internal activity scales and more frequent damage activities with smaller b-value. Furthermore, Correlation dimension Dm was positively correlated with the change of disturbance frequency, and it was smaller when the inclination angle was 45 °.

Provision of ramp-rate limitation from distribution networks to transmission systems as preventive action towards frequency disturbances

The high proliferation of Converter-Interfaced Renewable Energy Sources (CIRES) poses several challenges to electric power system operators regarding frequency stability and control. Some of these issues are related with the high active power Ramp Rates (RRs) of CIRES, stemming from their inertia-less and stochastic nature. To deal with such problems, Transmission System Operators (TSOs) often commit excessive amounts of conventional spinning reserves, while in weak Transmission Systems (TSs) regulations are imposed, aiming to mitigate RRs of CIRES. Moreover, several technical studies have proposed control approaches for RR Limitation (RRL). Nevertheless, the influence of RRL on frequency quality and mainly the impact of RRL control capability of small-scale CIRES, connected to Distribution Networks (DNs), on frequency deviations have not been fully explored and quantified. To fill this gap, a detailed investigation is performed in this paper. For this purpose, simulations are conducted on a simplified System Frequency Response (SFR) model as well as on an analytical power system model. The latter is a modified version of the IEEE 9-bus Test System, consisting of three conventional Synchronous Generators (SGs) and three Medium Voltage (MV) DNs, which include CIRES equipped with SuperCapacitors (SCs), thus presenting RRL control capability. To thoroughly evaluate the impact of RRL on frequency dynamics, a set of metrics is introduced and frequency duration curves are created for various scenarios. Finally, the influence of several factors, such as the total system inertia, the RRL target value, the SC size, etc, is quantified by using the proposed indices.

Fractional-PID and Its Parameter Optimization for Pumped Storage Units Considering the Complicated Conduit System

Speed governing control is significant in ensuring the stable operation of pumped storage units. In this study, a state-space equation mathematical model of the pumped storage governing system considering the complex hydraulic pipeline structure of the pumped storage plant is proposed to describe the system’s dynamic behaviors under small disturbance conditions. Considering the frequent operating condition transitions and the complicated nonlinear dynamic characteristics of the pumped storage units, the fractional-order PID (FOPID) scheme that possesses a higher degree of control freedom than the traditional PID scheme is discussed in detail. To optimize the control parameters of the unit governor, an improved gravitational search algorithm (IGSA) that combines the basic searching mechanisms of the gravitational search algorithm and chaotic search, elastic sphere boundary treatment, and elite guidance strategy is developed. Comparative studies have been carried out under frequency and load disturbance conditions. Simulation results indicate that the control performance of FOPID is better than that of PID under diverse operating conditions and the proposed IGSA has satisfactory parameter optimization capability.

A novel parallel multi-harmonic global multi-channel control algorithm for helicopter active vibration control

The vibrations of the helicopter fuselage are mainly induced by the rotor with blade pass frequency and the high order harmonics. The conventional filtered-x least mean square (FxLMS) control algorithm usually used a uniform convergence factor for all the harmonics which leads poor effect in controlling multi-harmonic vibration. In this paper, a novel parallel multi-harmonic global multi-channel (MHGMC) control method is proposed to suppress the multi-harmonic vibration components transmitted from the main rotor to the fuselage. Bandpass filters are used to separate multiple frequency components of the error signals, the control channel models are identified for the corresponding frequency range to independently control each frequency component, and the reconstruction of the reference input signals can be obtained from the separated error signal, effectively improving the performance of tracking interference signals. In addition, the coupling of the control channels is considered, and the global vibration optimization is taken as the control objective to update the weight coefficient of the controller. An active vibration control system of the helicopter main gearbox eight-strut installation configuration has been established. The simulation and experiment results show that the proposed controller has faster control convergence speed and better control effect of multiple harmonics than the conventional filtered-x least mean square algorithm, and the attenuations of the disturbing frequency harmonic components at all measurement points in the experiment are over 38dB. The experimental results of variable excitation also verify that the proposed control algorithm has excellent adaptability and strong robustness.

Effects of long-term proton pump inhibitor use on sexual hormones and sexual and reproductive health in female patients.

Proton pump inhibitors (PPIs) are widely used to treat a range of gastrointestinal diseases around the world. Long-term use of PPIs has been associated to a variety of undesirable effects. Although short-term therapy has been shown to have little or no effect on endocrine hormone in women, however, its long-term safety has received little attention. We aimed at evaluating long-term use of PPIs and its effects on female reproductive hormones as well as related clinical consequences. A cross-sectional study was conducted in two outpatient gastroenterology clinics in the province of Khyber Pakhtunkhwa. This study included female patients who had been using PPIs on a regular basis for 3 months or more. In total of 101 participants, patients with sexual complaints have significantly altered levels of prolactin (p = 0.05), estrogen (p < 0.001) and progesterone (p = 0.001) than patient without sexual complaints. The frequency of amenorrhea (p < 0.001), cyclic disturbances (p < 0.001), breast augmentation (p = 0.001) and painful breast (p = 0.004) were statistically significant in patients with raised serum prolactin values. Serum values of Sex hormone binding globulin SHBG (p < 0.001), estradiol (p = 0.002) and total testosterone (p < 0.001) were significantly altered between normal prolactin and hyperprolactinemic patients. These findings suggest that long-term PPI use may cause endocrine hormone disturbances leading to sexual difficulties in women.

Statistical Relationship of Ionospheric Disturbances Caused by Typhoon Extinction on the Sea

AbstractBased on the data of magnetic field and electronic density of SWARM, and Total Electron Content, this paper screened six typhoons that died out on the sea. We studied how typhoons affected the ionosphere when they died out without the influence of topography and other factors. The statistical results show that during the extinction of typhoons, the magnetic disturbances all appeared, and the electron density disturbances were observed in five typhoons. The frequency of the electronic density disturbance is slightly higher than the magnetic disturbance. The range of the electronic density disturbance is mostly five or six hundred kilometers and relatively concentrated. The range of the magnetic disturbance can reach about two thousand kilometers and is relatively scattered. Our results indicate that the extinction of typhoon may affect the ionosphere through acoustic gravity waves (AGWs). The AGWs is not generated by friction, but may be from the typhoon itself or a new phenomenon when the typhoon dies out.

3 The Menopause Transition in Women with Traumatic Brain Injury

Objective:All premenopausal women who survive traumatic brain injury (TBI) will eventually experience menopause. Challenges experienced by women with TBI are superimposed on challenges associated with hormonal changes in midlife. Some women with stressful life contexts such as TBI are more vulnerable to the added burdens of the menopause transition, potentiating its effects. Although it may be argued that TBI research correctly overrepresents the male experience given disparities in injury rates (4:1), there are important differences in how females and males age, their specific health needs, and the psychosocial context of midlife. Development of evidence-based interventions begins with understanding the experience of menopause after TBI, including where and when key problems may emerge.Participants and Methods:All participants were women 40-60 years old, not taking hormones (i.e., replacement therapy or other systematic hormones), with intact ovaries. Women with TBI were &gt; 2 years post injury, whose menstrual period returned after injury, and were living in the community. Severity of injury ranged from complicated-mild to severe TBI. Pre/peri and postmenopausal status was determined by presence/absence of menstrual period in previous 6 months, respectively. Eighteen common menopause symptoms (vasomotor, somatic, psychological, and cognitive) were assessed for presence and frequency (rarely-always), along with Quality of Life in Neurological Disorders (Neuro-QOL) Sleep Disturbance and Traumatic Brain Injury Quality of Life (TBIQOL) Anxiety, Depression, and Fatigue scales.Results:Overall, women with TBI (n = 68) showed greater presence and frequency of symptoms than women without TBI (n = 153), with fewer within-group differences by menopausal status. Among pre/peri-menopausal women, TBI and non-TBI groups did not significantly differ and showed small effect sizes on symptoms associated with changes in estrogen during menopause, including hot flashes, night sweats, bowel and bladder sequelae, and breast tenderness. However, pre/peri-menopausal women with TBI also endorsed body aches and headaches, as well as troubles with memory, focus, fatigue, cognitive concerns, sleep, and anxiety significantly more than their pre/peri-menopausal counterparts (all medium effect sizes). Among postmenopausal women, those with TBI had significantly greater frequency of hot flashes, crying spells, poor memory, worry, moodiness, panic attacks, sleep disturbance, and anxiety than women without TBI. Within TBI, only hot flashes and breast tenderness were greater in postmenopausal versus pre/peri-menopausal women. Within non-TBI, postmenopausal status was associated with significantly greater hot flashes, night sweats, restlessness, poor memory, irritability, sleep disturbance, and anxiety, with greater fatigue but not significantly.Conclusions:The findings support a model of TBI and menopause in which symptoms most closely associated with estrogen decline in pre/peri-menopause are generally similar between women with and without TBI, and symptoms that overlap with common TBI sequelae were generally more often present and frequently experienced among women with TBI versus non-TBI. We did not observe a synergistic or potentiating effect of TBI on menopause symptoms in post-menopause. These findings offer insight that contextualizes the experience of menopause symptoms among women with TBI. Such insights are essential for the development of treatment approaches that maximize health and wellbeing during the menopause transition for women with TBI.

18 Nightmares Independently Predict Neurobehavioral Symptoms in Adults with mTBI

Objective:To investigate the informative value of nightmares on neurobehavioral functioning in individuals with mild traumatic brain injury (mTBI) beyond general sleep disturbance.Participants and Methods:A sample of 146 adults with mTBI (mean age = 45.1±16.0), recruited from a specialized concussion treatment center, underwent an assessment of neurobehavioral functioning using the Behavioral Assessment Screening Tool (BAST), self-reported habitual sleep disturbance and quality (via the Pittsburgh Sleep Quality Index; PSQI), and reported nightmare frequency in the past two weeks.Results:Nightmare frequency was the strongest predictor of negative affect (ß = .362, p &lt;.001), anxiety (ß = .332, p &lt;.001), and impulsivity (ß = .270, p &lt;.001) after controlling for sex and age. Sleep disturbance accounted for the greatest variance in depression (ß = .493, p &lt;.001), burden from concussion (ß = .477, p &lt;.001), and fatigue (ß = .449, p &lt;.001) after controlling for sex and age.Conclusions:Nightmares independently associate with neurobehavioral symptoms and likely have differential etiology from reported sleep disturbance. Nightmare frequency was more strongly related to positive neurobehavioral symptoms (i.e., added factors that impact functioning, e.g., anxiety), while general sleep disturbance was associated with negative neurobehavioral symptoms (i.e., factors taken away that impact functioning, e.g., lack of energy). Our findings suggest that neuropsychological evaluations of individuals with mTBI should assess for sleep disturbance and nightmare frequency as risk factors for neurobehavioral barriers to functioning.

The closed-loop control method based on dual-port adaptive internal model control for fine image stabilization of space telescopes.

In view of the complex working environment of space astronomical telescopes, the influence of various disturbance sources on the imaging quality cannot be ignored. This paper focuses on compensating for the space telescope line-of-sight (LOS) deviation and suppressing the low-frequency disturbance problem in astronomical observation. A closed-loop control method based on dual-port adaptive internal model control (AIMC) for the fine image stabilization system (FISS) was proposed. To be specific, the fine guidance sensor (FGS) as the high-precision detection unit of the FISS calculates the telescope LOS deviation and sends it to the controller unit in real time. The controller unit drives the large-aperture fast steering mirror (FSM), which performs high-precision two-dimensional rotation to compensate for the telescope LOS deviation, according to the dual-port AIMC control algorithm. Moreover, the dual-port AIMC control method adds an AIMC loop on the basis of the feedback loop and adjusts the filter parameters adaptively according to the target angular velocity of the FSM, achieving higher disturbance suppression capability. The experimental results verify that the control method proposed can effectively compensate for the LOS deviation and suppress the composite frequency disturbance. In the 0-8Hz frequency band, the power spectral density integral values of the star centroid deviation in the X and Y directions of the FGS are, respectively, suppressed by 97.38% and 98.38%.

Fast-Frequency-Response Control Method for Electrode Boilers Supporting New Energy Accommodation

With the large-scale integration of new energy generation, represented by wind and photovoltaic power, into the power grid, the intermittency, randomness, and fluctuations of their output pose significant challenges to the safe and stable operation of the power system. Therefore, this paper proposes a control method for electrode boiler systems participating in rapid grid frequency response based on a fuzzy control strategy. This method improves the traditional electrode boiler control strategy, giving it characteristics similar to those of synchronous generators in terms of active power–frequency droop, allowing it to actively adjust active power based on system frequency disturbances. Furthermore, it optimizes its control performance indicators using fuzzy algorithms. The simulation results on the Matlab/Simulink platform demonstrate that the modified electrode boiler control system, when applying this method, can effectively address power disturbances in the system, reduce system frequency deviations, and contribute to enhancing the grid frequency regulation capability and system stability.

Isolation and Identification of Periodic Disturbances in BLDC Motors

A high-gain linear observer is proposed for online identification and reconstruction of a periodic disturbance. It is assumed that the frequency of the periodic disturbance is known, but its amplitude and phase are unknown. This is not a stringent assumption since such supposition can be easily characterized for disturbances like cogging torque, or bearing defects, both well-known problems in the control of electric machines. The observer design is based on the internal model principle in combination with a high-gain observer. Numerical results are included to validate the estimation of the periodic disturbance even when another disturbance of a different frequency is added. The estimated disturbance can be used to design a controller for reducing the disturbance effect. Alternatively, the estimated disturbance can be used for fault detection like in the case of gears and bearing faults, or simply to characterize the cogging torque of a particular machine.

Interaction between functional capability and sleep quality at midterm after total knee arthroplasty: a Japanese retrospective cohort study

No report has clarified the frequency and interacting factors affecting sleep disturbance among Asian patients at midterm after total knee arthroplasty (TKA). This study aimed to evaluate the frequency of sleep disturbance at midterm after TKA in a Japanese cohort and to identify intervening factors for sleep. We hypothesized that residual knee pain and decreased functional capability negatively interact with sleep quality after TKA. A total of 209 Japanese participants (average age: 77.1 ± 8.3 years; postoperative follow-up period: 4.5 ± 1.9 years) who underwent primary TKA for knee osteoarthritis were included in this study. Sleep quality, satisfaction, pain, functional capability, joint awareness, and mental condition were evaluated using the Pittsburgh Sleep Quality Index (PSQI), Knee Society Score (KSS) 2011, Forgotten Joint Score (FJS)-12, and 12-Item Short-Form Health Survey (SF-12) Mental Component Summary (MCS). Multivariable analysis was performed to determine the influencing factors on PSQI. The scores for the PSQI, satisfaction with pain level while lying in bed, pain during level walking, functional activity category in the KSS 2011, awareness of the artificial joint in bed at night in the FJS-12, and SF-12 MCS were 6.7 ± 3.0, 5.8 ± 1.8, 1.6 ± 2.3, 62 ± 22, 1.5 ± 1.4, and 56 ± 9.3 on average, respectively. Sleep disturbance (PSQI ≥ 5.5) occurred in 54% of the Japanese participants. Multivariable analysis revealed that high functional capability was a significant factor associated with sleep quality improvement (p < 0.05). Decreased functional capability, not residual knee pain, negatively interacted with sleep quality. The sleep disturbance rate was high during the middle postoperative period after TKA in the Japanese cohort.

Chronic disturbance induces attenuation of the acute glucocorticoid response in an urban adapter, the dark-eyed junco

Urban birds’ stress response frequently differs in magnitude from non-urban conspecifics. This urban phenotype may reflect response to selection, sorting during colonization of urban environments, developmental plasticity, or phenotypic flexibility in response to urban environments. We investigated whether exposure to one characteristic of an urban environment, chronic disturbance, could induce an attenuated acute glucocorticoid response over a short time in adult non-urban dark-eyed juncos (Junco hyemalis), which, if true, would support the phenotypic flexibility hypothesis. We tested this during the period of spring gonadal recrudescence. We simulated a high-disturbance urban-like environment by exposing non-urban experimental birds to chronic disturbance (30-min psychological stressors 4x/day for 3 weeks); controls were minimally disturbed. We found that chronically disturbed birds had a lower acute corticosterone response after 3 weeks of treatment. Baseline corticosterone was not affected. Chronically disturbed birds had less body fat and lower body condition than controls at the end of the experiment, although on average all birds gained weight over the course of the experiment. Feathers grown during the experiment did not show an effect of the disturbance treatment on feather corticosterone or fault bars, although captive-grown feathers had lower corticosterone and more fault bars than wild-grown feathers. We conclude that adult male juncos have the capacity to attenuate their acute corticosterone response in an environment with high frequency of disturbance, potentially facilitating colonization of urban habitats. Future research may show whether successful urban colonists differ from unsuccessful species in this regard.

The Barrens Flora of Wisconsin’s Northwest Sands Ecological Landscape

The barrens of Wisconsin’s Northwest Sands Ecological Landscape are a dynamic mosaic shifting between dry forests and woodlands to open, prairie-like communities depending on the frequency of disturbance. We examined the floristics of eight sites within the barrens that were selected to represent the full latitudinal gradient of the ecological landscape. In the course of this study, we collected 2,213 voucher specimens representing 71 plant families, 217 genera, and 404 taxa. We compared the sites to one another using floristic quality assessments, the Sørensen–Dice similarity index, and various qualitative comparisons. The barrens flora becomes less diverse as you move from the southwest to the northeast. Prairie species are more common and dominant in the southwestern sites, and northern dry forest species are more common and dominant in the northeastern sites.

An Anti-Islanding Protection Method Based on Voltage-Synchronous Impedance Angle Measurements

Grid-tied distributed generators (DGs) need to be equipped with anti-islanding protection to avoid the impact of unplanned islanding, which would affect system stability, auto-reclosing, and personal safety. Among the active anti-islanding protections, impedance measurements based on signal injection have the advantages of a low non-detection zone (NDZ) and are less prone to maloperation during grid disturbances; however, there are problems with signal interference in multi-DG systems. Hence, the impedance angle measurement method with signals injected synchronously is proposed. In this method, each DG injects phase-coherent signals to detect islanding using zero-cross points of the voltage (ZCPV) to avoid the protection failures caused by signal interference. An islanding identification criterion based on the measured impedance angle is proposed by analyzing the impedance characteristics of grid connection and islanding, which avoids the influence of variation of the DG operation state on islanding detection. Finally, we present a signal injection strategy and performance analysis in combination with an existing DG control platform, avoiding additional hardware investment. RTDS-based simulation verification shows that the proposed method can 100% avoid DG maloperation due to voltage and frequency disturbances during grid-connected operation and exit operation within 2 s when islanding occurs.

Evaluation the results of electromagnetic compatibility of a prototype device for ear stimulation in patients with tinnitus.

&lt;b&gt;&lt;br&gt;Aim:&lt;/b&gt; The aim of the study was to evaluate the results of electromagnetic compatibility of a prototype device for ear stimulation in patients with tinnitus.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Material and methods:&lt;/b&gt; The electromagnetic compatibility tests of the prototype device for electro- and magnetostimulation of the hearing organ were carried out at the Center for Attestation and Certification Tests OBAC Sp. z o. o. in Gliwice in 2020. The following product standards were used: PN-EN 60601-1-2:2015-11 - medical electrical equipment (general requirements for basic safety and essential functioning; PN-EN 55011:2012 - industrial, scientific and medical equipment [characteristics of radio frequency disturbances] ) PN-EN 61000-3-2:2014-10 - electromagnetic compatibility (EMC), permissible levels of harmonic current emissions (phase load current ≤ 16 A).&lt;/br&gt; &lt;b&gt;&lt;br&gt;Results:&lt;/b&gt; The level of expanded uncertainty in the measurement of conducted disturbances in the range of 0.150-30MHz does not exceed the level specified in the PN-EN-55016-4-2:2011 standard. In the study of the emission of radiated disturbances up to 1GHz in the frequency range of 30-1000MHz (PN-EN 55011:2012 standard), it was found that the setting of the EUT during the tests was in accordance with the requirements of the standard. The level of expanded uncertainty in the measurement of radiated disturbances in the 30-1000MHz range does not exceed the level specified in the PN-EN 55016-4-2:2011 standard. The measured current harmonic levels (phase power supply current ≤16A) with a frequency range of 50Hz-2kHz do not exceed the permissible levels specified in the PN-EN 61000-3-2:2014-10 standard. The test of resistance to the magnetic field at the frequency of the power grid (PN-EN 61000-4-8: 2010 standard also showed that the setting of the EUT during the tests was in accordance with the requirements of the standard and the result was positive.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Conclusions:&lt;/b&gt; Testing of immunity to radiated radio frequency electromagnetic field (PN-EN 61000-4-3:2007 +A1:2008+A2:2011 standard) and testing of resistance to magnetic field at power frequency (PN-EN 61000-4-8 standard :2010) did not exceed the level specified in the standard and showed a positive result. The measured harmonic levels of the network current (phase supply current ≤16A) with the frequency range 50Hz-2kHz do not exceed the permissible levels specified in the PN-EN 61000- 3-2:2014-10 standard for a class A device.&lt;/br&gt.

Addressing the Primary and Subharmonic Resonances of the Swing Equation

A research investigation is undertaken to gain a more comprehensive understanding of the primary and subharmonic resonances exhibited by the swing equation. The occurrence of the primary resonance is characterised by amplified oscillatory reactions, voltage instability, and the possibility for system failure. The phenomenon of subharmonic resonance arises when the frequency of disturbance is a whole-number fraction of the natural frequency. This results in the occurrence of low-frequency oscillations and the potential for detrimental effects on equipment. The objective of this study is to expand upon the current literature regarding the impacts of primary resonance and enhance comprehension of subharmonic resonance in relation to the stability of a specific power system model. The analytical and numerical tools are utilised to investigate the fundamental principles of this resonant-related problem, aiming to provide an effective control solution. This choice is driven by the model’s complex nonlinear dynamical behaviour, which offers valuable insights for further analysis. This analysis includes the Floquet Method, the Method of strained parameters, and the concept of tangent instability in order to provide an extension to existing literature relating to primary and subharmonic resonances, taking into account the dynamic and bifurcation characteristics of the swing equation. This objective will be achieved through the utilisation of both analytical and numerical methods, enabling the identification of specific indicators of chaos that can contribute to the safe operation of real-world scenarios.

Associations between Normal-Weight Obesity and Disturbances in the Lipid Profile of Young Adults.

Normal-weight obesity (NWO) is characterized by normal body mass index (BMI) but high body fat percentage (%BF) that increases the risks of cardiometabolic comorbidities. Accurate assessment and interpretation of body composition data are necessary to reduce these risks. To compare the cardiometabolic profile of individuals with NWO and normal %BF and evaluate the associated risk factors. A cross-sectional study was conducted with 222 Brazilian adults from a university community, of whom 157 had NWO and 65 had normal BMI and %BF (non-NWO). All participants reported being asymptomatic and without underlying health conditions. Socioeconomic, lifestyle, food intake, anthropometry, body composition measures (using dual-energy radiological absorptiometry), and lipid and glycemic profiles were evaluated. A p < 0.05 was established as significant. The median age of the participants was 23 years (interquartile range: 21 to 25), and most were female (67.1%). No significant differences were found in blood pressure, age, or physical activity levels between the NWO and non-NWO groups. However, the frequency of lipid profile disturbances was higher in the NWO group (54%) compared to the non-NWO group (34%) (p < 0.006). Neck circumference, %BF, and lipid profile disturbances were positively associated with NWO. Individuals with NWO have a worse cardiometabolic profile than those without NWO, and this condition is associated with important biomarkers. Addressing these outcomes is important for preventing long-term cardiometabolic complications. Accurate assessment and interpretation of body composition data, regardless of BMI, are crucial in this scenario.

Wheeled Robot Formation Control under Uncertainty Including Adaptive Rejection of Harmonic Disturbances with Arbitrary Frequencies

This work addresses an adaptive regulation problem for formation control of uncertain unicycle-like dynamical robots. The control goal is to drive a finite number of robots to a prescribed formation despite the presence of multi-sinusoidal input disturbances of unknown frequencies and despite uncertainties in the unicycle model, (mass and inertia’s are unknown). Numerical Simulations were done to illustrate the viability of the suggested strategy. The only measurements available for control are the orientation of the unicycles and the relative positions and velocities according to a given connectivity graph.

Impact frequency variation of self-excited oscillation pulsed supercritical carbon dioxide jets

In order to obtain the impact frequency of resonant coal breaking by self-excited oscillation pulsed supercritical carbon dioxide (SC-CO2) jet, large eddy simulation was used to analyze the formation and development process of self-excited oscillation pulsed SC-CO2 jet, the variation of jet impact frequency in the nozzle and the free flow field, and the variation of jet impact frequency at different positions in the jet axis and under different cavity lengths. The test device of jet impact frequency was developed, and experiments were performed to verify the conclusions of the numerical simulations. The results show that the frequency of the self-excited oscillation pulsed SC-CO2 jet is different in the nozzle and the free flow field. In the nozzle, the frequency generated by the fluid disturbance is the same, and the jet frequency at the exit of the nozzle is consistent with that inside the nozzle. In the free flow field, due to the compressibility of CO2, the pressure, velocity and other parameters of SC-CO2 jets have obvious fluctuation patterns. This feature causes the impact frequency of the self-excited oscillation pulsed SC-CO2 jet to decrease gradually in the axis. Changing the cavity length allows the adjustment of the jet impact frequency in the free flow field by affecting the disturbance frequency of the self-excited oscillation pulsed SC-CO2 jet inside the nozzle.