Resonance Stabilization Research Articles

Determiantion of energy characteristics of material destruction in the crushing chamber of the vibration crusher

The crushing equipment is characterized by a significant energy-consuming system during the crushing workflow. The current trend in the development of such processes puts forward requirements for the development of new or improvement of existing energy-saving equipment. The essence of the solution to the problem in this work is determined by using resonant modes, which are inherently the most effective. The practical implementation of the resonance mode has been achieved taking into account the conditions for the interaction of the resonant vibration crusher with the material at the stages of its destruction. The degree of the stress-strain state of the material is taken into account, which was a prerequisite for identifying the potential for the development of a vibration load. Composed equations of motion based on a substantiated discrete-continuous model of a vibration crusher and processing material. An approach is applied to determine the stepwise destruction of the material with the determination of the required degree of energy. This methodological approach made it possible to reveal the nature of the process of material destruction, where energy costs at the stages of crack formation, their development and final destruction are taken into account. It was revealed that the greatest energy consumption during the operation of crushers goes into the kinetic energy of the crushing plates and the potential energy of deformation of the springs. The proposed model is common for any design of a vibration machine and its operating modes. The stable resonance mode has made it possible to significantly reduce the energy consumption for the course of the technological process of material grinding. The results obtained are used to improve the calculation methods for vibratory jaw and cone crushers that implement the corresponding energy-saving stable zones of the working process.

A review ofSTATCOMcontrol for stability enhancement of power systems with wind/PVpenetration: Existing research and future scope

In recent years, the development of renewable energy sources (RESs) and their integration with the conventional power network have increased significantly. Due to the power grid transformation brought about by the large penetration of power electronics converter-based RESs such as wind and solar photovoltaic (PV), the operation and control of the interconnected power system has become a challenging task with respect to sustaining its stability and reliability. Power systems are confronted by several new stability issues because the dynamic behavior of converter-interfaced renewable sources differs from conventional generation. In this respect, static synchronous compensator (STATCOM), a shunt connected flexible AC transmission system (FACTS), is recognized as a fundamental solution for maintaining power system stability. This paper presents a thorough and state-of-the-art review of STATCOM control in wind- and/or PV-interfaced power systems for enhancing system performance by addressing key stability issues related to rotor angle stability, voltage stability, and resonance stability. A comprehensive analysis of various control techniques of STATCOM based on conventional, adaptive, nonlinear, predictive, robust, and coordinated control and soft computing techniques is provided. Furthermore, the function of the grid-side converter of the wind/PV plant as a STATCOM is also evaluated. Finally, the shortcomings of existing research are highlighted, current control challenges are presented, and several topics for future research are suggested. This paper provides researchers the opportunity to consider the current state of research and develop new control schemes for STATCOM to further improve the stability of modern power grids.

Liquid crystal-amplified optofluidic biosensor for ultra-highly sensitive and stable protein assay

Protein assays show great importance in medical research and disease diagnoses. Liquid crystals (LCs), as a branch of sensitive materials, offer promising applicability in the field of biosensing. Herein, we developed an ultrasensitive biosensor for the detection of low-concentration protein molecules, employing LC-amplified optofluidic resonators. In this design, the orientation of LCs was disturbed by immobilized protein molecules through the reduction of the vertical anchoring force from the alignment layer. A biosensing platform based on the whispering-gallery mode (WGM) from the LC-amplified optofluidic resonator was developed and explored, in which the spectral wavelength shift was monitored as the sensing parameter. The microbubble structure provided a stable and reliable WGM resonator with a high Q factor for LCs. It is demonstrated that the wall thickness of the microbubble played a key role in enhancing the sensitivity of the LC-amplified WGM microcavity. It is also found that protein molecules coated on the internal surface of microbubble led to their interactions with laser beams and the orientation transition of LCs. Both effects amplified the target information and triggered a sensitive wavelength shift in WGM spectra. A detection limit of 1 fM for bovine serum albumin (BSA) was achieved to demonstrate the high-sensitivity of our sensing platform in protein assays. Compared to the detection using a conventional polarized optical microscope (POM), the sensitivity was improved by seven orders of magnitude. Furthermore, multiple types of proteins and specific biosensing were also investigated to verify the potential of LC-amplified optofluidic resonators in the biomolecular detection. Our studies indicate that LC-amplified optofluidic resonators offer a new solution for the ultrasensitive real-time biosensing and the characterization of biomolecular interactions.

Experimental and kinetic modeling investigation on 2,5-hexanedione oxidation in a jet-stirred reactor

Unique resonance stabilization features of R and QOOH radicals of 2,5-hexanedione [CH3C(=O)CH2CH2C(=O)CH3] facilitated the investigation on the roles of carbonyl group in the oxidation of ketones. This work presents the first study on the speciation from the oxidation of 2,5-hexanedione. A fuel-lean (ϕ=0.5) 2,5-hexanedione/O2/Ar mixture was investigated in a jet-stirred reactor (JSR) operated at atmospheric pressure, over a temperature range of 600–900 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to acquire detailed speciation information. A detailed kinetic mechanism was proposed based on the “reaction classes” strategy and validated against the current measurements. No obvious low-temperature reactivity was observed under the investigated conditions, and the reason was attributed to the unfavored ROO = QOOH isomerization reactions of both two RO2 radicals, while the energetically favored HO2-elimination reactions produce inert HO2 radicals in the low-temperature regime. β-scission reactions dominate the consumption of fuel radicals. The prediction of fuel reactivity strongly depends on the reactions involving the small hydrocarbon species and H-atom abstraction reactions. The competition between the reaction pair of CH3+HO2 = CH3O+OH and CH3+HO2 = CH4+O2 is the most influential factor for the fuel reactivity in the studied temperature regimes. Based on the experimental observations and kinetic modeling analyses, fuel consumption and major intermediates formation pathways in 2,5-hexanedione were illustrated.

Stretchable self-tuning MRI receive coils based on liquid metal technology (LiquiTune)

Magnetic resonance imaging systems rely on signal detection via radiofrequency coil arrays which, ideally, need to provide both bendability and form-fitting stretchability to conform to the imaging volume. However, most commercial coils are rigid and of fixed size with a substantial mean offset distance of the coil from the anatomy, which compromises the spatial resolution and diagnostic image quality as well as patient comfort. Here, we propose a soft and stretchable receive coil concept based on liquid metal and ultra-stretchable polymer that conforms closely to a desired anatomy. Moreover, its smart geometry provides a self-tuning mechanism to maintain a stable resonance frequency over a wide range of elongation levels. Theoretical analysis and numerical simulations were experimentally confirmed and demonstrated that the proposed coil withstood the unwanted frequency detuning typically observed with other stretchable coils (0.4% for the proposed coil as compared to 4% for a comparable control coil). Moreover, the signal-to-noise ratio of the proposed coil increased by more than 60% as compared to a typical, rigid, commercial coil.

Load-bearing capacity and resonance stability of inelastic beams and plane trusses with initial defects

PurposeThe purpose of this paper is to contribute to the solution of the buckling and resonance stability problems in inelastic beams and wooden plane trusses, taking into account geometric and material defects.Design/methodology/approachTwo sources of non-linearity are analyzed, namely the geometrical non-linearity due to geometrical imperfections and material non-linearity due to material defects. The load-bearing capacity is obtained by the rheological-dynamical analogy (RDA). The RDA inelastic theory is used in conjunction with the damage mechanics to analyze the softening behavior with the scalar damage variable for stiffness reduction. Based on the assumed damages in the wooden truss, the corresponding external masses are calculated in order to obtain the corresponding fundamental frequencies, which are compared with the measured ones.FindingsRDA theory uses rheology and dynamics to determine the structures' response, those results in the post-buckling branch can then be compared by fracture mechanics. The RDA method uses the measured P and S wave velocities, as well as fundamental frequencies to find material properties at the limit point. The verification examples confirmed that the RDA theory is more suitable than other non-linear theories, as those proved to be overly complex in terms of their application to the real structures with geometrical and material defects.Originality/valueThe paper presents a novel method of solving the buckling and resonance stability problems in inelastic beams and wooden plane trusses with initial defects. The method is efficient as it provides explanations highlighting that an inelastic beam made of ductile material can break in any stage from brittle to extremely ductile, depending on the value of initial imperfections. The characterization of the internal friction and structural damping via the damping ratio is original and effective.

Dynamically stable single frequency ring resonator from diode pumped Nd:YAG modules with 55.6 W of output power

A Nd:YAG rod single-frequency ring laser based on side-pumped commercial modules is presented. Thermally induced birefringence compensation was applied in a dynamically stable resonator providing 55.6 W of continuous, linearly polarized, TEM00 output. The particular case of a symmetric ring resonator containing one or two focusing rods and a pair of curved mirrors was analyzed and a design technique is presented, allowing for easy, continuous shaping of the stability limits by changing only the distances in the resonator.

Subharmonics and superharmonics of the weak field in a driven two-level quantum system: Vibrational resonance enhancement.

We consider a quantum two-level system in bichromatic classical time-periodic fields, the frequency of one of which far exceeds that of the other. Based on systematic separation of timescales and averaging over the fast motion a reduced quantum dynamics in the form of a nonlinear forced Mathieu equation is derived to identify the stable oscillatory resonance zones intercepted by unstable zones in the frequency-amplitude plot. We show how this forcing of the dressed two-level system may generate the subharmonics and superharmonics of the weak field in the stable region, which can be amplified by optimization of the strength of the high frequency field. We have carried out detailed numerical simulations of the driven quantum dynamics to corroborate the theoretical analysis.

Synthesis of Dihydroisoquinoline and Dihydropyridine Derivatives via Asymmetric Dearomative Three-Component Reaction

Synthesis of Dihydroisoquinoline and Dihydropyridine Derivatives via Asymmetric Dearomative Three-Component Reaction

Tunable and stable localized surface plasmon resonance in SrMoO4 for enhanced visible light driven nitrogen reduction

Photocatalytic nitrogen reduction for the green synthesis of ammonia at ambient conditions has been slowed by the narrow light harvesting range, low activity and high charge recombination of photocatalysts. Plasmonic semiconducting nanomaterials are becoming the promising candidates for nitrogen photofixation because of the broad absorption spectrum, rich defects and hot carriers. In the present study, plasmonic SrMoO4 is developed by regulating the concentration of oxygen vacancies that are accompanied in the reduction process from Mo6+ to Mo5+. The stable and tunable localized surface plasmon resonance (LSPR) absorption in visible and near infrared light range makes the wide bandgap SrMoO4 utilize the solar energy more efficiently. Energetic electrons from both the intrinsic band excitation and the LSPR excitation enable the reduction of dinitrogen molecules thermodynamically in ultrapure water to ammonia. This work provides a unique clue to design efficient photocatalysts for nitrogen fixation.

Resolving Entangled Reactivity Modes through External Electric Fields and Substitution: Application to E2/SN2 Reactions.

In this study, we explore strategies to resolve entangled reactivity modes. More specifically, we consider the competition between SN2 and E2 reaction pathways for alkyl halides and nucleophiles/bases. We first demonstrate that the emergence of an E2-preference is associated with an enhancement of the magnitude of the resonance stabilization in the transition-state (TS) region, resulting from the improved mixing of electrostatically stabilized valence bond structures into the TS wavefunction. Subsequently, we show that the TS resonance energy can be tuned selectively and rationally either through the application of an oriented external electric field directed along the C-C axis of the alkyl halide or through a regular substitution approach of the C-C moiety. We end our study by demonstrating that the insights gained from our analysis enable one to rationalize the main reactivity trends emerging from a recently published large database of competing SN2 and E2 reaction pathways.

The effects of pectin and wax on the characteristics of oil-in-water (O/W) emulsions.

The study was aimed to investigate characteristics of emulsion containing pectin, wax, maltodextrin, and carotenoid enriched flaxseed oil by means of stability, rheology, particle size, and low-resolution of time domain nuclear magnetic resonance (NMR) relaxometry measurements. Emulsions were prepared with different carotenoid enriched-flaxseed oil concentrations (6%, 9%, 12%, and 15% w/w) and ratios of maltodextrin/(pectin+wax) (3:1, 6:1, 9:1, and 12:1g/g). Percentage separation of 12% oil 12:1 ratio of maltodextrin/(pectin+wax) (g/g), 15% oil 9:1, and 12:1 ratios of maltodextrin/(pectin+wax) (g/g) of emulsions was determined as 2.0 ± 0.5%,4.0 ± 0.5%,and 8.0 ± 0.5%,respectively. No separation was observed in other emulsions. The rheological behavior of emulsions was best described by the power law model. When the concentration of pectin+wax in the emulsion decreased, the n values of the emulsions were close to 1, indicating that the fluid behavior approaches Newtonian behavior. Moreover, the emulsion viscosity was observed to increase when pectin and wax concentrations in the emulsion increased. The increase in pectin and wax concentration in emulsions with oil contents of 6% and 9% resulted in a reduction in the average particle size. However, if the oil concentration in the emulsions was 12% or more, the increase in the ratio of maltodextrin/(pectin+wax) (g/g) led to a decrease in the average particle size. NMR transverse relaxation times (T2 ) of emulsions were measured and results showed that T2 values for almost all formulations decreased when the ratio of maltodextrin/(pectin+wax) reduced. PRACTICAL APPLICATION: Study results demonstrated that the combination of pectin and wax together with maltodextrin as a filling material could be an alternative way to improve emulsion stability. Findings of this study provided useful guidance for the future studies about the potential use of pectin, wax, and maltodextrin as wall material in encapsulation of oils or in producing edible films.

Diminished ketone interconversion, hepatic TCA cycle flux, and glucose production in D-β-hydroxybutyrate dehydrogenase hepatocyte-deficient mice

ObjectiveThroughout the last decade, interest has intensified in intermittent fasting, ketogenic diets, and exogenous ketone therapies as prospective health-promoting, therapeutic, and performance-enhancing agents. However, the regulatory roles of ketogenesis and ketone metabolism on liver homeostasis remain unclear. Therefore, we sought to develop a better understanding of the metabolic consequences of hepatic ketone body metabolism by focusing on the redox-dependent interconversion of acetoacetate (AcAc) and D-β-hydroxybutyrate (D-βOHB). MethodsUsing targeted and isotope tracing high-resolution liquid chromatography-mass spectrometry, dual stable isotope tracer nuclear magnetic resonance spectroscopy-based metabolic flux modeling, and complementary physiological approaches in novel cell type-specific knockout mice, we quantified the roles of hepatocyte D-β-hydroxybutyrate dehydrogenase (BDH1), a mitochondrial enzyme required for NAD+/NADH-dependent oxidation/reduction of ketone bodies. ResultsExogenously administered AcAc is reduced to D-βOHB, which increases hepatic NAD+/NADH ratio and reflects hepatic BDH1 activity. Livers of hepatocyte-specific BDH1-deficient mice did not produce D-βOHB, but owing to extrahepatic BDH1, these mice nonetheless remained capable of AcAc/D-βOHB interconversion. Compared to littermate controls, hepatocyte-specific BDH1 deficient mice exhibited diminished liver tricarboxylic acid (TCA) cycle flux and impaired gluconeogenesis, but normal hepatic energy charge overall. Glycemic recovery after acute insulin challenge was impaired in knockout mice, but they were not more susceptible to starvation-induced hypoglycemia. ConclusionsKetone bodies influence liver homeostasis. While liver BDH1 is not required for whole body equilibration of AcAc and D-βOHB, loss of the ability to interconvert these ketone bodies in hepatocytes results in impaired TCA cycle flux and glucose production. Therefore, through oxidation/reduction of ketone bodies, BDH1 is a significant contributor to hepatic mitochondrial redox, liver physiology, and organism-wide ketone body homeostasis.

Parameter co-design of active damping loop and grid current controller for a 3-phase LCL-filtered grid-connected inverter

Under non-ideal grid conditions, especially the harmonic grid condition, the proportional resonant controller with multiple harmonic resonant controllers (HR-PR controller) is recommended to provide high quality grid currents for the 3-phase LCL-filtered grid-connected inverter. Besides, in order to solve the resonance problem, the active damping loop with the grid-side currents feedback only is preferred. However, parameters of the HR-PR controller and the active damping loop both affect the performance of LCL filter resonance suppression and stability of the inverter, which is analyzed in this paper. Moreover, the stability constraint and the resonance suppression constraint is derived to maintain the good ability of LCL filter resonance suppression and satisfy the stability requirements of the inverter. Considering the wide control bandwidth for the HR-PR controller, a co-design method of the active damping loop and HR-PR controller is proposed in this paper. By introducing the Lagrange multiplier method, the proposed co-design method obtains the optimized parameters for the active damping loop and grid currents controller in z-domain appropriately. A prototype of 3-phase LCL-filtered three-level neutral point clamped grid-connected inverter is established to validate the proposed method.

Design and development of Schiff’s base (SB)-modified polylactic acid (PLA) antimicrobial film for packaging applications

SB compounds were synthesized from (para, ortho, meta)-phenylenediamine as a cross-linking agent through vanillin. The chemical structure of the formed SB complexes is confirmed by FT-IR spectroscopy. Among the three complexes, para-phenylenediamine (p-SB), possessing a stable resonance structure with the lowest steric repulsion, was obtained in the highest yield of 87%. Hence, the present work focused on reducing the brittle behavior and improving the antimicrobial activity of PLA by reacting it with p-SB. FT-IR investigation revealed the existence of an intermolecular hydrogen bonding between PLA and SB, which led to an increased toughness in the PLA–p-SB complex. This is further confirmed through SEM analysis. The tensile and contact angle measurements determined an improvement in mechanical properties and hydrophobic nature of the PLA–p-SB film. DSC results demonstrated an increase in flexibility, which indicated a 10 °C reduction in glass transition temperature (Tg) of PLA–p-SB films. The antimicrobial activity of the PLA–p-SB films had a maximum of 15 mm zone of inhibition, which was found to be more effective than the neat PLA film. PLA–p-SB coating on Kraft paper showed improved mechanical and barrier properties than neat PLA coatings and could be tried as a possible replacement for conventional synthetic packaging materials.Graphic abstract

Fitness-to-drive for glioblastoma patients: Guidance from the Swiss Neuro-Oncology Society (SwissNOS) and the Swiss Society for Legal Medicine (SGRM).

The management of brain tumour patients who would like to resume driving is complex, and needs multidisciplinary input and a consensus among treating physicians. The Swiss Neuro-Oncology Society (SwissNOS) and the Swiss Society for Legal Medicine (SGRM) aim to provide guidance on how to assess “fitness-to-drive” of glioblastoma patients and to harmonise the relevant procedures in Switzerland. At several meetings, Swiss neuro-oncologists discussed common practices on how to advise patients with a stable, i.e., non-progressive, glioblastoma, who wish to resume driving after the initial standard tumour treatment. All participants of the SwissNOS meetings were invited twice to return a questionnaire (modified Delphi process) on specific tools/procedures they commonly use to assess “fitness-to-drive” of their patients. Answers were analysed to formulate a tentative consensus for a structured and reasonable approach. Consensus on minimum requirements for a “fitness-to-drive” programme for glioblastoma patients could be reached among Swiss neuro-oncologists. The recommendations were based on existing guidelines and expert opinions regarding patients with seizures, visual disturbances, cognitive impairment or focal deficits for safe driving. At this point in time, the Swiss neuro-oncologists agreed on the following requirements for glioblastoma patients after the initial standard therapy and without a seizure for at least 12 months: (1) stable cranial magnetic resonance imaging (MRI) according to Response Assessment in Neuro-Oncology (RANO) criteria, to be repeated every 3 months; (2) thorough medical history, including current or new medication, a comprehensive neurological examination at baseline (T0) and every 3 months thereafter, optionally an electrocencephalogram (EEG) at baseline; (3) ophthalmological examination including visual acuity and intact visual fields; and (4) optional neuropsychological assessment with a focus on safe driving. Test results have to be compatible with safe driving at any time-point. Patients should be informed about test results and optionally sign a document. We propose regular thorough clinical neurological examination and brain MRI, optional EEG, neuropsychological and visual assessments to confirm “fitness-to-drive” for glioblastoma patients after initial tumour-directed therapy. The proposed “fitness-to-drive” assessments for glioblastoma patients serves as the basis for a prospective Swiss Pilot Project GLIODRIVE (BASEC ProjectID 2020-00365) to test feasibility, adherence and safety in a structured manner for patients who wish to resume driving. Research will focus on confirming the usefulness of the proposed tools in predicting “fitness-to-drive” and match results with events obtained from the road traffic registry (Strassenverkehrsamt).

Development of an L-band resonator optimized for fast scan EPR imaging of the mouse head.

To develop a novel resonator for high-quality fast scan electron paramagnetic resonance (EPR) and EPR/NMR co-imaging of the head and brain of mice at 1.25 GHz. Resonator dimensions were scaled to fit the mouse head with maximum filling factor. A single-loop 6-gap resonator of 20 mm diameter and 20 mm length was constructed. High resonator stability was achieved utilizing a fixed position double coupling loop. Symmetrical mutually inverted connections rendered it insensitive to field modulation and fast scan. Coupling adjustment was provided by a parallel-connected variable capacitor located at the feeding line at λ/4 distance. To minimize radiation loss, the shield around the resonator was supplemented with a planar conductive disc that focuses return magnetic flux. Coupling of the resonator loaded with the mouse head was efficient and easy. This resonator enabled high-quality in vivo 3D EPR imaging of the mouse head following intravenous infusion of nitroxide probes. With this resonator and rapid scan EPR system, 4 ms scans were acquired in forward and reverse directions so that images with 2-scan 3,136 projections were acquired in 25 s. Head images were achieved with resolutions of 0.4 mm, enabling visualization of probe localization and uptake across the blood-brain barrier. This resonator design provides good sensitivity, high stability, and B1 field homogeneity for in vivo fast scan EPR of the mouse head and brain, enabling faster measurements and higher resolution imaging of probe uptake, localization, and metabolism than previously possible.

On Indirect Excitation of Lateral Vibrations of the Table of the Electrodynamic Stand Suspended on Viscoelastic Shock Absorbers

Modern machines and aerospace facilities are equipped with rather complex, multi-link high-level vibration protection systems. Therefore, it is of interest to carry out work on the formation of dynamic models of vibration-protective properties of the apparatus, taking into account the properties of their real design features. The plane-parallel motion of a viscoelastic suspended rigid body with an axis of symmetry and imitating the motion of the table of an electrodynamic stand is considered. In the calculated dynamic scheme, the action of the suspension membranes and the hanging shock absorber is represented as the action of some linear springs. It is assumed that a periodic perturbing force (the action of a pulsating magnetic field) directed vertically is applied at the body’s center of gravity. Nonlinear integro-differential equations of motion are compiled, in expansions of trigonometric functions and power series, only small second2 nd order are kept. The method of averaging is used to reduce to normal coordinates. The conditions for indirect excitation of axial lateral vibrations (torsional vibrations about the horizontal axis) under the stability of the parametric resonance of the vertical are obtained. Formulas providing the suspendet object are obtained.

Upqc Based Solar Grid Maintained System For Variable Power And Voltage Conditions

This research shows that utilization of unified power quality Modified conditioner (UPQMC) to wipe out power quality matter. The solar PV board through a boost modifier is coordinated at the direct current-connection of UPQMC. To remove the power reflections from existed methods and extreme power losses from PV boards can be adjusted using UPQMC. The UPQMC comprises of the combination of shunt circuit also arranged the inverter (INV). The voltage concentration, power & quality (PQ) issues, swell, sag, peak shoots are trained, by the arrangements of INV network. For administration with the current related issues, for example current balancing, resonance stability, etc are managed by the shunt INV is utilized in UPQMC. Thus the UPQMC performs multiple tasks, for example, the voltage connected issue, paek overshoot, stability, irradiance, issues. The demonstration of solar based PV coordinated UPQMC is impersonate & utilized with power reproduction programming

Tunable and stable localized surface plasmon resonance in SrMoO4 for enhanced visible light driven nitrogen reduction

Tunable and stable localized surface plasmon resonance in SrMoO4 for enhanced visible light driven nitrogen reduction