Initial Frequency Research Articles

Prescribing Cascades of Loop Diuretics and Anti-vertigo Drugs Following Treatment with Gabapentinoids and Benzodiazepines: Prescription Sequence Symmetry Analysis of a Large-Scale Claims Database Including Japanese Older Adults.

Gabapentinoids (GBP) and benzodiazepines (BZ) are commonly prescribed in older adults and their package inserts list edema and vertigo as adverse drug reactions. These adverse drug reactions may be treated with symptomatic drug therapies without discontinuing the culprit drugs or decreasing their dose, thereby initiating a prescribing cascade and often resulting in polypharmacy. Whether prescribing cascades occur in the treatment of edema and dizziness among Japanese patients treated with GBP and BZ has not been investigated, including treatment with mirogabalin, a class drug of GBP marketed in Japan. We aimed to investigate prescribing cascades with GBP-induced and BZ-induced edema and dizziness treated with loop diuretics (LD) and anti-vertigo drugs (AVD), respectively, among older adults. A prescription sequence symmetry analysis design was used to detect signals of prescribing cascades associated with edema and dizziness induced by GBP and BZ (exposure drugs). Loop diuretics and AVD were the outcome drugs used to identify prescribing cascades following the initiation of exposure drugs. The study population consisted of enrollees of a large-scale health claims database provided by DeSC Healthcare, Inc., between April 2014 and March 2021. Subjects eligible for a prescription sequence symmetry analysis were patients aged ≥65 years prescribed an outcome drug within 90 days before and after exposure drug initiation. A signal of a prescribing cascade was detected if secular trend-adjusted sequence ratios were statistically significant on comparison of the frequencies of outcome drug initiation before and after exposure drug initiation. We identified 2671 patients with prescriptions of a GBP-LD combination, 4009 with a GBP-AVD combination, 8675 with a BZ-LD combination, and 9462 with a BZ-AVD combination. The adjusted sequence ratios for GBP-LD and BZ-LD cascades were significantly larger than one (adjusted sequence ratio [95% confidence interval], 1.69 [1.56-1.83]; 1.35 [1.29-1.41], respectively), indicating positive signals of prescribing cascades. No signal was detected for the GBP-AVD or BZ-AVD cascade (0.89 [0.83-0.94]; 0.90 [0.87-0.94], respectively). The adjusted sequence ratio for the mirogabalin cascade was higher than that for pregabalin (2.23 [1.84-2.71] vs 1.59 [1.46-1.73]). Our study provides good evidence that LD-prescribing cascades associated with edema would be a class effect of GBP and BZ. Edema emerging around 1 month after GBP initiation should be carefully differentiated from pathological edema, and undue LD prescription as a prescribing cascade should be avoided.

Vibrational resonance mechanism in the high-order-degradation bistable system and its application in fault diagnosis

Bearings play an important role in the rotating machinery. Timely fault detection and maintenance can prevent catastrophic incidents caused by bearing faults. As one of the advanced techniques to extract the weak characteristics of bearing fault, the methods based on the vibrational resonance (VR) mechanism can effectively amplify the weak characteristics. However, first, the effect of the barrier width and the barrier height on the VR mechanism has not been investigated. Second, the application of the VR mechanism requires accurate prior knowledge, which limits its application. In this paper, the high-order-degradation bistable potential is decoupled so that the effect of the barrier width or the barrier height on the VR mechanism can be easily analyzed. Then, the initial frequency detection technique based on the 1.5-dimension envelope spectrum and the logical operation of sets is proposed, which helps to adaptively provide accurate prior knowledge for the application of the VR mechanism in the high-order-degradation bistable system (HBSVR). Finally, experimental results show that the proposed method is more advantageous in detecting single and compound faults compared with other state-of-the-art methods.

Smith–Watson–Topper Parameter in Partial Slip Bimodal Oscillations of Axisymmetric Elastic Contacts of Similar Materials: Influence of Load Protocol and Profile Geometry

Based on a very fast numerical procedure for the determination of the subsurface stress field beneath frictional contacts of axisymmetric elastic bodies under arbitrary 2D oblique loading, the contact mechanical influences of loading parameters and contact profile geometry on the Smith–Watson–Topper (SWT) fatigue crack initiation parameter in elastic fretting contacts with superimposed normal and tangential oscillations are studied in detail. The efficiency of the stress calculation allows for a comprehensive physical analysis of the multi-dimensional parameter space of influencing variables. It is found that a superimposed normal oscillation of the contact can significantly increase or decrease the SWT parameter, depending on the initial phase difference and frequency ratio between the normal and tangential oscillation. Written in proper non-dimensional variables, the rounded flat punch always exhibits smaller values of the SWT parameter, compared to a full paraboloid with the same curvature, while the truncated paraboloid exhibits larger values. A small superimposed profile waviness also significantly increased or decreased the SWT parameter, depending on the amplitude and wave length of the waviness. While both the load protocol and the profile geometry can significantly alter the SWT parameter, the coupling between both influencing factors is weak.

A Nurse-Led Algorithm for Diagnosing Urinary Tract Infection in Homebound Older Adults.

We designed a nurse-led algorithm to standardize urinary tract infection (UTI) diagnosis for older adults receiving home-based medical care. Aims of this pilot quality improvement study were to reduce the frequency of empiric antibiotic therapy initiated without a urinalysis and urine culture (UA/UC) first being obtained, reduce antibiotic use without a concomitant increase in emergency department (ED) visits or hospital admissions, and ensure stakeholders' satisfaction with algorithm use. A nurse-led diagnostic algorithm was designed and pilot-tested to address challenges and standardize diagnosis of UTI in a population of homebound older adults. In pre/post data analysis, algorithm implementation was associated with improved frequency of obtaining UA/UC before empiric antibiotic therapy was initiated, but the overall rate of antibiotic use for UTI did not decrease. No increase in ED or hospital admissions was identified. Use of a diagnostic algorithm for UTI among homebound older adults was associated with reduced frequency of empiric antibiotic initiation for suspected UTI without a UA/UC first being obtained. More rigorous study is needed to confirm and expand on these findings. [Research in Gerontological Nursing, 17(2), 92-97.].

Associations of childhood poly-adversity with alcohol problems among undergraduates: adolescent alcohol use trajectories and drinker self-schema

Objective Undergraduate drinking is associated with childhood adversity, early alcohol experience, and drinker self-schema. However, the pathway linking childhood adversity to undergraduate drinking problems remains undefined. This study aimed to identify the effects of childhood poly-adversity on the sequelae of adolescent alcohol-use trajectory, drinker self-schema, and alcohol problems among undergraduates. We also examined whether adolescent alcohol-use trajectory and drinker self-schema mediated the effects of childhood poly-adversity on undergraduate alcohol problems. Methods Baseline data from an ongoing prospective study, which included 851 first- and second-year full-time college students in Taiwan, were used. An anonymous online questionnaire was administered. Results The results showed that low poly-adversity and high poly-adversity were associated with the mean of initial alcohol use frequency during adolescence and further alcohol problems at college than those with no adversity. High poly-adversity was also associated with the increase in alcohol use frequency during adolescence. Both initial and increase in alcohol use frequency were associated with higher drinker self-schema scores and further alcohol problems. The indirect effects of high poly-adversity on undergraduate alcohol problems were mediated through adolescent alcohol-use trajectories and drinker self-schema. Conclusion Findings suggest that early identification of childhood poly-adversity and interventions to decrease adolescent drinking may prevent the formation of drinker self-schema and reduce undergraduate drinking problems.

Effects of Brief Parent Coaching on the Communication Skills of Preschoolers With Autism Spectrum Disorder and Limited Verbal Ability

The publicly funded early intervention program for preschoolers with autism spectrum disorder (ASD) in Nova Scotia, Canada, uses the pivotal response treatment (PRT) model. Parents are coached in use of PRT strategies during their children’s first week of treatment. We explored whether parents of older preschoolers with limited verbal ability learned to implement PRT strategies with fidelity after brief coaching and whether PRT strategy use was associated with gains in children’s communication skills. We coded precoaching and postcoaching parent–child play episodes of 39 children (4.4–5.5 years) with limited verbal skills for parents’ PRT fidelity and children’s correct responding to language opportunities and frequency of initiations. Parents’ use of PRT strategies significantly improved, as did children’s responsiveness to parent-provided language opportunities. This study provides evidence for the utility of brief parent coaching in PRT for older preschoolers with ASD whose verbal skills are limited.

Factors associated with frequent buprenorphine / naloxone initiation in a national survey of Canadian emergency physicians.

To identify individual and site-related factors associated with frequent emergency department (ED) buprenorphine/naloxone (BUP) initiation. BUP initiation, an effective opioid use disorder (OUD) intervention, varies widely across Canadian EDs. We surveyed emergency physicians in 6 Canadian provinces from 2018 to 2019 using bilingual paper and web-based questionnaires. Survey domains included BUP-related practice, demographics, attitudes toward BUP, and site characteristics. We defined frequent BUP initiation (the primary outcome) as at least once per month, high OUD prevalence as at least one OUD patient per shift, and high OUD resources as at least 3 out of the following 5 resources: BUP initiation pathways, BUP in ED, peer navigators, accessible addiction specialists, and accessible follow-up clinics. We excluded responses from sites with <50% participation (to minimize non-responder bias) and those missing the primary outcome. We used univariate analysis to identify associations between frequent BUP initiation and factors of interest, stratifying by OUD prevalence. We excluded 3 responses for missing BUP initiation frequency and 9 for low response rate at one ED. Of the remaining 649 respondents from 34 EDs, 374 (58%) practiced in metropolitan areas, 384 (59%) reported high OUD prevalence, 312 (48%) had high OUD resources, and 161 (25%) initiated BUP frequently. Age, gender, board certification and years in practice were not associated with frequent BUP initiation. Site-specific factors were associated with frequent BUP initiation (high OUD resources [OR 6.91], high OUD prevalence [OR 4.45], and metropolitan location [OR 2.39],) as were individual attitudinal factors (willingness, confidence, and responsibility to initiate BUP.) Similar associations persisted in the high OUD prevalence subgroup. Individual attitudinal and site-specific factors were associated with frequent BUP initiation. Training to increase physician confidence and increasing OUD resources could increase BUP initiation and benefit ED patients with OUD.

Frequency of same-day contraceptive initiation, recent unprotected intercourse, and pregnancy risk: a prospective cohort study of multiple contraceptive methods

BackgroundSame-day start removes barriers to contraceptive initiation and may reduce the risk of unintended pregnancy. Same-day start may be appropriate for all contraceptive methods, but we lack data comparing methods. ObjectivesTo assess the frequency of same-day initiation among six contraceptive methods selected for “same-day start” among new contraceptive users and describe the efficacy of same-day start first cycle pregnancy risk by all contraceptive methods and by each method. Study DesignUsing prospective data from the HER Salt Lake Contraceptive Initiative, we identified and assessed outcomes for participants initiating a new method of contraception beyond the first seven days of their menstrual cycle (same-day start). Enrolled participants at four family planning clinics in Salt Lake County, Utah between September 2015-March 2017 received their method of choice regardless of their cycle day or recent unprotected intercourse. All participants self-reported last menstrual period data and unprotected intercourse events in the previous 2 weeks. We excluded participants that received care immediately after or within two weeks of abortion care. Clinical electronic health records provided information on contraceptive method initiation and use of oral emergency contraception. Participants reported pregnancy outcomes in 1-, 3-, and 6-month follow-up surveys with clinic verification to identify any pregnancy resulting from same-day initiation. The primary outcomes report the frequency of same-day start use and first cycle pregnancy risk among same-day start users of all contraceptive methods. The secondary outcomes include frequency of and pregnancy risk in the first cycle of use among same-day start contraception users by method. We also report frequency of unprotected intercourse within 5 days and 6-14 days of contraception initiation, frequency of concomitant receipt of oral emergency contraception with initiation of ongoing contraception, and pregnancy risk with these exposures. We analyzed pregnancy risk by contraceptive method initiated same-day and assessed for simultaneous use of oral emergency contraception. ResultsOf the 3,568 individuals enrolled, we identified the majority as same-day start users (n=2,575/3,568, 72.2%), with one in eight of those reporting unprotected intercourse in the previous 5 days (n=322/2,575, 12.5%) and one in ten reporting unprotected intercourse 6-14 days prior to contraceptive method initiation (n=254/2,575, 9.9%). We identified 11 pregnancies among same-day start users (0.4%, 95% CI 0.2%-0.7%) compared to 1 (0.1%. 95% CI 0.002%-0.6%) among those who initiated contraception within seven days from the last menstral period. Users of oral hormonal contraception and vaginal hormonal methods reported the highest 1st cycle pregnancy rates (1.0 – 1.2%). Among same-day start users, 174 (6.8%) received oral emergency contraception at enrollment in conjunction with another method. Of the same-day user who received emergency contraception at initiation, 4 (2.3%) pregnancies were reported. Conclusion(s)Same-day start is common and associated with a low pregnancy risk. Using the “any method, any-time” approach better meets contraceptive clients’ needs and maintains a low risk of pregnancy.

Salinity gradient power generation in sinusoidal nanochannels

Salinity gradient power generation based on nanochannels has drawn much attention for its green and sustainable advantages. However, previous studies have tended to focus on regularly shaped nanochannels, while rough and irregular surfaces are naturally formed during the preparation of nanochannels (similar to sinusoidal nanochannels). In this paper, a model of salinity gradient energy conversion in sinusoidal nanochannels is established. The impacts of the geometrical parameter dimensions of the sinusoidal channel (including initial phase, channel length, average radius, amplitude, and angular frequency) on the power generation performance under different salinity gradients are systematically investigated. The results show that the sinusoidal nanochannel has better salinity gradient power generation performance than cylindrical nanochannel. It obtains the best power generation performance when the initial phase is zero. Besides, increasing the nanochannel length facilitates ion selectivity and energy conversion efficiency. At high concentration difference, decreasing the average radius or increasing the amplitude help increase the maximum output power and enhance the energy conversion efficiency. The maximum output power of about 1.27 pW and energy conversion efficiency of about 32.8% were obtained by optimizing the sinusoidal channel amplitudes. It is also found that increasing the angular frequency is favorable to improving energy conversion performance at the high concentration difference. These results provide helpful information for designing and optimizing salinity gradient energy conversion systems.

Energy spectra and fluxes of turbulent rotating Bose–Einstein condensates in two dimensions

We investigate the scaling of the energy cascade in a harmonically trapped, turbulent, rotating Bose-Einstein condensate in two dimensions. We achieve turbulence by injecting a localized perturbation into the condensate and gradually increasing its rotation frequency from an initial value to a maximum. The main characteristics of the resulting turbulent state depend on the initial conditions, rotation frequency, and ramp-up time. We analyze the energy and the fluxes of kinetic energy by considering initial profiles without vortices and with vortex lattices. In the case without initial vortices, we find the presence of Kolmogorov-like scaling (k−5/3) of the incompressible kinetic energy in the inertial range. However, with initial vortex lattices, the energy spectrum follows Vinen scaling (k−1) at transient iterations. For cases with high rotating frequencies, Kolmogorov-like scaling emerges at longer durations. We observe positive kinetic energy fluxes with both initial states across all final frequencies, indicating a forward cascade of incompressible and compressible kinetic energy.

Bimetallic PdAg clusters loaded on hierarchical self-pillared pentasil zeolite as efficient catalysts for formic acid dehydrogenation

In the present study, siliceous self-pillared pentasil (SPP) zeolite with regular mesopores was synthesized and used as a support for anchoring bimetallic PdAg clusters through a facile impregnation-reduction method. The as-prepared PdAg/SPP catalysts with different Pd/Ag ratios were demonstrated to catalyze formic acid dehydrogenation for hydrogen production. XRD results confirmed the formation of PdAg alloy on the surface of SPP zeolite. The Pd7Ag3/SPP catalyst showed high activity at 80 °C with an initial turn-over frequency (TOF) of 1263.6 h−1, proving the strategy using hierarchical SPP zeolite as carrier is advantageous over bulky zeolites for making highly active formic acid dehydrogenation catalysts.

A New Kilohertz Gravitational-wave Feature from Rapidly Rotating Core-collapse Supernovae

We present self-consistent three-dimensional core-collapse supernova simulations of a rotating 20M ⊙ progenitor model with various initial angular velocities from 0.0 to 4.0 rad s−1 using the smoothed particle hydrodynamics code SPHYNX and the grid-based hydrodynamics code FLASH. We identify two strong gravitational-wave features with peak frequencies of ∼300 Hz and ∼1.3 kHz in the first 100 ms postbounce. We demonstrate that these two features are associated with the m = 1 deformation from the proto-neutron star (PNS) modulation induced by the low-T/∣W∣ instability, regardless of the simulation code. The 300 Hz feature is present in models with an initial angular velocity between 1.0 and 4.0 rad s−1, while the 1.3 kHz feature is only present in a narrower range, from 1.5 to 3.5 rad s−1. We show that the 1.3 kHz signal originates from the high-density inner core of the PNS, and the m = 1 deformation triggers a strong asymmetric distribution of electron antineutrinos. In addition to the 300 Hz and 1.3 kHz features, we also observe one weaker but noticeable gravitational-wave feature from higher-order modes in the range between 1.5 and 3.5 rad s−1. Its initial peak frequency is around 800 Hz, and it gradually increases to 900–1000 Hz. Therefore, in addition to the gravitational bounce signal, the detection of the 300 Hz, 1.3 kHz, the higher-order mode, and even the related asymmetric emission of neutrinos could provide additional diagnostics for estimating the initial angular velocity of a collapsing core.

Frequency monitoring analysis of milling edge chatter in composites using WPD for frequency band selection

In the milling process of composite materials, the initial chatter frequency is not obvious and is easily swamped by the rest of the signals, making frequency monitoring difficult, so the study proposes a chatter frequency monitoring method based on frequency cancellation algorithms and wavelet packet decomposition. The results of the experiments shown that the frequency cancellation algorithm can successfully remove invalid signals, such as spindle rotation frequency and cutter tooth frequency, and only keep the necessary signals, at which point the chattering frequency may be observed at a frequency of roughly 1333 Hz. The influence of the frequency bands s5, s9, s10, s12, and s13 after de-frequency removal should be avoided because they all have a low energy share of roughly 23 %, 0.9 %, 5 %, 10 %, and 16 %, respectively, and are less sensitive to chatter. For milling edge depths of 0.5 mm, 2 mm, and 4 mm, the average chatter thresholds were around 3.27, 2.9, and 2.89, respectively. It was challenging to pinpoint the chatter of the system because the empirical modal decomposition observed an average chatter energy entropy of just 1.55 and found that its fluctuations at the milling edge depth junction were insignificant. On the other hand, the chattering could be plainly seen since the energy entropy experienced a substantial and dramatic fluctuation at the intersection of the milling edge depth when it was about 2.9, 2.6, and 2.5, respectively. The experimental findings demonstrated that the frequency cancellation technique and wavelet packet decomposition-based chattering frequency monitoring approach can precisely track the chattering state of the system.

Non-contact electromagnetic controlled metamaterial beams for low-frequency vibration suppression

To address the challenge of suppressing extremely-low frequency vibration and noise in precision instruments and equipment, a novel non-contact metamaterial beams is proposed in this paper. The resonators of the metamaterial beams integrate negative stiffness mechanism and electromagnetic damping tuning system. Based on the magnetic dipole theory and the electromagnetic induction law, the mechanical model of magnetic resonator is established. The band structure and transmission spectrum of the metamaterial beams are obtained by transfer matrix method. Besides, the results of numerical simulations are used to verify the accuracy of theoretical results. The result shows that the negative stiffness can be controlled by nonlinear magnetic force among the magnets. Based on this mechanism, the bandgap frequency can be reduced to a minimum of 50Hz. Then, the method of combining electromagnetic damping and negative impedance circuit is proposed to form a tuning system which can reduce the initial frequency of the bandgap to 4Hz. Interestingly, the proposed bandgap control mechanism achieves the extremely-low bandgap while broadens the bandwidth relatively, which overcomes the deficiency of traditional quasi-zero-stiffness metamaterials that reduce the bandgap frequency while causing the bandwidth to narrow. This study is expected to provide valuable ideas for the application of metamaterials in the field of low-frequency vibration and noise reduction.

A novel double-layer active equalization scheme for lithium-ion batteries combining wireless power transfer

Battery packs inconsistency is inevitable in the use of series-connected cells. For packs equalization in confined environments, direct electrical contact is unpermitted. To address this issue, a novel double-layer equalization topology is proposed. It combines a wireless equalizer for inter-group equalization with a wired active equalizer for intra-group equalization. Firstly, current and voltage of intra-group equalization and inter-group equalization are introduced. Then, the Thevenin equivalent model is developed and parameter identification of the model is performed using the least squares method with a forgetting factor. In addition, the intra-group equalization parameters and inter-group equalization parameters are designed to improve the equalization performance. For different currents corresponding to different cell resistances, the duty cycle of the buck circuit is analyzed to achieve a constant equalization current. The optimal switching frequency and equalization method for intra-group equalization are designed to improve the equalization effect. Finally, an equalization experiment with eight cells is designed to validate the effectiveness of the proposed topology and strategy. The experimental results demonstrate that the designed topology has better equalization performance under different initial SOC distributions and switching frequencies. It verifies that the equilibrium model is able to effectively solve the inconsistency of the series-connected battery packs.

Mass formulas for individual black holes in merging binaries

We give formulas for individual black hole masses in a merger, by using Newtonian physics, in terms of the three measured quantities in the detector: the initial wave frequency f 1, the maximum detected frequency (chirp frequency) f 2, and the time elapse τ between these two frequencies. Newtonian gravity provides an excellent pedagogical tool to understand the basic features of gravitational wave observations, but it must be augmented with the assumption of gravitational radiation from General Relativity for accelerating masses as there is no gravitational wave Newtonian gravity. The simplest approach would be to consider a binary system of two non-spinning masses (two black holes) circling their common center of mass. All the computations can be done within Newtonian physics, but the General Relativistic formula for the power carried by gravitational waves is required in this scheme. It turns out there is a subtle point: for the consistency of this simple, yet pedagogical computation, taking the lowest order power formula from General Relativity leads to complex individual masses. Here we remedy this problem and suggest a way to write down an average power formula coming from perturbative General Relativity.

Research on flexible beam-type nonlinear vibration isolators suitable for low frequencies

Ship vibration not only causes safety issues, but also easily generates noise pollution. Therefore, this paper introduces the quasi-zero stiffness (QZS) vibration isolator to solve the problem of low-frequency vibration. In terms of static analysis, this paper proposes a discretized beam constraint model (DBCM) to study the static properties of flexible beams with large deformation, and the finite element analysis (FEA) verifies the accuracy of DBCM. Regarding dynamic analysis, this paper combines the harmonic balance method (HBM) and the pseudo-arc length method (PALM) to analyze the dynamic response and explore the influence of excitation and damping ratio on the response stability. In addition, the performance of equivalent linear isolators is compared, revealing significant advantages of QZS isolator in terms of isolation bandwidth and peak transmissibility. The experimental data demonstrates that QZS isolator’s initial isolation frequency (2.14 Hz) is 68.5% lower than that of linear isolators (6.79 Hz), and the isolation efficiency at 5.35 Hz can reach 90%, making it suitable for low-frequency isolation. Furthermore, experimental data validate the accuracy of the theoretical model and FEA. The static and dynamic theoretical models can optimize the structural parameters of flexible beams and serve as valuable inspiration and reference for designing and improving isolator.

Multi band multi polarised fractal antenna for white space TV band

ABSTRACT Designing a fractal antenna for white space TV band frequencies is the main goal of the suggested work. In this design 4 iteration Koch snowflakes patch is used to get multiband. As the number of iterations increased size of the antenna is going to reduce. Further 4th iteration Koch snowflakes slots have been created in the patch. By introducing a fourth iteration cross slot into the ground plane, three bands have been created. Circular polarisation is attained through the incorporation of cross slots in the ground plane, inducing a phase shift between vertically and horizontally polarised electromagnetic waves. The antenna primarily operates within the last frequency bands (686–806 MHz) with linear polarisation. However, it can also function in the initial frequency band (487–540 MHz) with left-hand circular polarisation. The physical size if antenna is reduced by 38 mm with a gain of 4.5dBi. Axial ratio bandwidth (481–552 MHz) is 71 MHz. Axial ratio bandwidth is 18 MHz more as compared to impedance bandwidth. The same antenna can work in linear polarisation as well as circular polarisation. Multi-polarised, multiband antenna with impedance bandwidth of 10.3% (1st band) and 16.08% (last band) is designed for white space TV band frequencies.

Non-Markovian effects on the performance of a quantum Otto refrigerator

Quantum thermodynamics is an important infrastructure for developing and performing many tasks in quantum technologies. In this paper, we propose a model for constructing an Otto refrigerator thermal machine via an auxiliary system and Markovian reservoir. Moreover, the proposed model induces Markovian and/or non-Markovian regimes on refrigerant systems. By increasing the coupling strength between the refrigerant and auxiliary systems, non-Markovian behaviors arise in different thermodynamic quantities. In addition, the different amounts of quantum thermodynamics, namely work, heat and coefficient of performance, are investigated as a function of the initial frequency of the refrigerant system. Our results show that the memory effects between the open system and the environment can enhance the power of the proposed Otto refrigerator, particularly in the finite-time strokes of the refrigerator, under some specific circumstances.

An Investigation of the Energy Harvesting Capabilities of a Novel Three-Dimensional Super-Cell Phononic Crystal with a Local Resonance Structure.

Using the piezoelectric (PZT) effect, energy-harvesting has become possible for phononic crystal (PnC). Low-frequency vibration energy harvesting is more of a challenge, which can be solved by local resonance phononic crystals (LRPnCs). A novel three-dimensional (3D) energy harvesting LRPnC is proposed and further analyzed using the finite element method (FEM) software COMSOL. The 3D LRPnC with spiral unit-cell structures is constructed with a low initial frequency and wide band gaps (BGs). According to the large vibration deformation of the elastic beam near the scatterer, a PZT sheet is mounted in the surface of that beam, to harvest the energy of elastic waves using the PZT effect. To further improve the energy-harvesting performance, a 5 × 5 super-cell is numerically constructed. Numerical simulations show that the present 3D super-cell PnC structure can make full use of the advantages of the large vibration deformation and the PZT effect, i.e., the BGs with a frequency range from 28.47 Hz to 194.21 Hz with a bandwidth of 142.7 Hz, and the maximum voltage output is about 29.3 V under effective sound pressure with a peak power of 11.5 µW. The present super-cell phononic crystal structure provides better support for low-frequency vibration energy harvesting, when designing PnCs, than that of the traditional Prague type.