Critical Issues of Vanadium-Based Cathodes Towards Practical Aqueous Zn-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) are gaining significant attention for their numerous advantages, including high safety, high energy density, affordability, and environmental friendliness. However, the development of ZIBs has been hampered by the lack of suitable cathode materials that can store Zn2+ with high capacity and reversibility. Currently, vanadium-based materials with tunnel or layered structures are widely researched owing to their high theoretical capacity and diversified structures. However, their long-term cycling stability is unsatisfactory because of material dissolution, phase transformation, and restrictive kinetics in aqueous electrolytes, which limits their practical applications. Different from previous reviews on ZIBs, this review specifically addresses the critical issues faced by vanadium-based cathodes for practical aqueous ZIBs and proposes potential solutions. Focusing on vanadium-based cathodes, their ion storage mechanisms, the critical parameters affecting their performance, and the progress made in addressing the aforementioned problems are also summarized. Finally, future directions for the development of practical aqueous ZIB are suggested.

Diimidazolium Salt HBDIM: An Easily Available, Low-Cost, CageCarbene Precursor with Broad Applications in Transition Metal-Catalyzed Reactions.

The preparation of diimidazolium salt HBDIM 1, a precursor for a di-NHCs ligand, from cheap and easily available agent hexabenzylhexaazaisowurtzitane (HBIW) is reported. Under basic conditions, HBDIM undergoes facile deprotonation to in situ generate CageCarbene, which could efficiently coordinate to transition-metals, such as, Au, Cu or Pd, to give the corresponding bimetallic complexes 2-4. These complexes were isolated and fully characterized, including X-ray diffraction of their single crystals. It was found that the steric hinderance of CageCarbene is similar to that of SIMes but smaller than that of IPr, and electronically, CageCarbene is a strong σ-donator similar to SIMes and a stronger σ-donator than IPr. Further studies showed that complexes 2-4 were highly reactive to catalyze up to 17 reactions. Control experiments utilizing a N-benzyl-substituted monoimidazolium salt showed much lower catalytic reactivity when it was bound to Au or Cu, but exhibited similar reactivity for the Pd complex. Kinetic studies showed that the low reactivity of the monodentate carbene-ligated Au or Cu complex was due to the low stability of the complex under the reaction conditions.

Association between age and loneliness in different residential type and gender groups: evidence from China.

BACKGROUND: Age has been identified as a prominent predictor of loneliness, although the findings about the relationship between age and loneliness are inconclusive. This study examines the relationship between age and loneliness in the context of China, with a focus on residential and gender differences. METHODS: Data were from the Chinese General Social Survey (CGSS) of 2017. A total of 3899 respondents were included. Loneliness was measured using a three-item Short Loneliness Scale. Age, squared terms of age, residential type, gender, and other socio-demographic characteristics were included in the study. Regression analyses were conducted among the total sample and subgroups of different gender and residential type subgroups, to investigate the association between age and loneliness. RESULTS: There is a reverse U-shaped tendency between age and loneliness that peaks at the age of 47. This tendency is true of the male subgroup, that peaks at the age of 55, while the female respondents do not share that tendency. The inverted U-shaped distribution holds true for urban but not for rural residents. The female respondents reported a higher level of loneliness than the male. The rural respondents reported higher loneliness than their counterparts. CONCLUSIONS: This study demonstrates that an inverted U-shaped tendency between age and loneliness existed for the entire group, and the male and urban subgroups. Implications for service and practice are proposed based on the empirical findings.

Discomfort estimation for aircraft cabin noise using linear regression and modified psychoacoustic annoyance approaches.

Appropriate sound quality models for noise-induced discomfort are necessary for a better acoustic comfort design in the aircraft cabin. This study investigates the acoustic discomfort in two large passenger aeroplanes (i.e., planes A and B). We recorded the noise at 21 positions in each aircraft cabin and selected 42 stimuli ranging from 72 to 81 dB(A) during the cruising flights. Twenty-four participants rated the noise discomfort by the absolute magnitude estimation method. The discomfort values in the middle section of the aircraft cabin are 10% points higher than in the front or rear section. The discomfort magnitude was dominated by loudness and influenced by roughness and sharpness. A multiple linear (MA) discomfort model was established, accounting for the relationship between the discomfort and sound quality metrics (i.e., loudness, sharpness, and roughness). The MA model estimated noise discomfort better than the Zwicker and other (i.e., More and Di) psychoacoustic annoyance (PA) models. We modified the coefficients of independent variables in the formulations of Zwicker, Di, and More PA models, respectively, according to the present experimental results. The correlation coefficients between the estimated and measured values of the modified models were at least 20% points higher than the original ones.

Hewettite ZnV6 O16 ⋠8H2 O with Remarkably Stable Layers and Ultralarge Interlayer Spacing for High-Performance Aqueous Zn-Ion Batteries.

Aqueous Zn-ion batteries (ZIBs) are promising candidates for grid-scale energy storage because of their intrinsic safety, low-cost and high energy-intensity. Vanadium-based materials are widely used as the cathode of ZIBs, especially A2 V6 O16 ⋅ nH2 O (AVO, A=NH4 + , Na, K). However, AVO suffers from serious dissolution, phase transformation and narrow gallery spacing (∼3 Å), leading to poor cycling stability and rate capability. Herein, we unveiled the root cause of the performance degradation in the AVO cathode and therefore developed a new high-performance cathode of ZnV6 O16 ⋅ 8H2 O (ZVO) for ZIB. Through a method of ion exchange induced phase transformation, AVO was converted to hewettite ZVO with larger gallery spacing (∼6 Å) and more stable V6 O16 layers. ZVO cathode thus constructed delivers a high capacity of 365 and 170 mAh g-1 at 0.5 and 15 A g-1 , while 86 % and 70 % of its capacity are retained at 0.5 A g-1 after 300 cycles and at 15 A g-1 after 10000 cycles, substantially better than conventional AVO.

Enhancing Energy Conversion Efficiency and Durability of Alkaline Nickel-Zinc Batteries with Air-Breathing Cathode.

Despite their high output voltage and safety advantages, rechargeable alkaline nickel-zinc batteries face significant challenges associated with the cathodic side reaction of oxygen evolution, which results in low energy efficiency (EE) and poor stability. Herein, we propose to leverage the side oxygen evolution reaction (OER) in nickel-zinc batteries by coupling electrocatalysts for oxygen reduction reactions (ORR) in the cathode, thus constructing an air breathing cathode. Such a novel battery (Ni-ZnAB), designed in a pouch-type cell with a lean electrolyte, exhibits an outstanding EE of 85 % and a long cycle life of 100 cycles at 2 mA cm-2 , which are significantly superior to those of traditional Ni-Zn batteries (54 %, 50 cycles). Compared to Ni-Zn, the enhanced EE of Ni-ZnAB is attributed to the contribution from ORR, while the improved cycling stability is because the stability of the anode, cathode and electrolyte are also enhanced in Ni-ZnAB. Furthermore, an ultrahigh stability of 500 cycles with an average EE of 84 % at 2 mA cm-2 was achieved using a mold cell with rich electrolyte, demonstrating the strong application potential of Ni-ZnAB.

Vehicle Stability Analysis under Extreme Operating Conditions Based on LQR Control.

Under extreme working conditions such as high-speed driving on roads with a large road surface unevenness coefficient, turning on a road with a low road surface adhesion coefficient, and emergency acceleration and braking, a vehicle's stability deteriorates sharply and reduces ride comfort. There is extensive existing research on vehicle active suspension control, trajectory tracking, and control methods. However, most of these studies focus on conventional operating conditions, while vehicle stability analysis under extreme operating conditions is much less studied. In order to improve the stability of the whole vehicle under extreme operating conditions, this paper investigates the stability of a vehicle under extreme operating conditions based on linear quadratic regulator (LQR) control. First, a seven degrees of freedom (7-DOF) dynamics model of the whole vehicle is established based on the use of electromagnetic active suspension, and then an LQR controller of the electromagnetic active suspension is designed. A joint simulation platform incorporating MATLAB and CarSim was built, and the CarSim model is verified by real vehicle tests. Finally, the stability of the vehicle under four different ultimate operating conditions was analyzed. The simulation results show that the root mean square (RMS) values of body droop acceleration and pitch angle acceleration are improved by 57.48% and 28.81%, respectively, under high-speed driving conditions on Class C roads. Under the double-shift condition with a low adhesion coefficient, the RMS values of body droop acceleration, pitch acceleration, and roll angle acceleration are improved by 58.25%, 55.41%, and 31.39%, respectively. These results indicate that electromagnetic active suspension can significantly improve vehicle stability and reduce driving risk under extreme working conditions when combined with an LQR controller.

Dipole-based beamforming method for locating dipole sources with unknown orientations in three-dimensional domains.

In conventional delay-and-sum beamforming, the monopole source assumption may cause a dipole source to be misinterpreted, leading to incorrect mapping results. A dipole-based beamforming method is proposed that is an extension of monopole-based conventional beamforming. The dipole sources could be located with no prior knowledge of the source orientation, and the unknown orientation is arbitrary in a three-dimensional domain. The location of a dipole source is determined by calculating the beamforming results at predefined orientations and positions using a dipole-based propagation function, and the final beamforming result at each scanning point is determined by the maximum value at the predefined orientations. Numerical simulations and experiments are performed on rotating dipole sources, and satisfactory results for the location of these dipole sources are obtained with different orientations.

Beamforming correction for the singular problem in identifying rotating sources with non-uniform directivity.

Identification of rotating sources with non-uniform directivity has been paid much attention in the field of aeroacoustic measurements over recent years. Singularities may be produced on the source map by using the rotating source identifier based on the multipole model due to zeros of the directivity function. A correction method is proposed to remove the influence of source directivity on source imaging and restrain the singular problem. De-Dopplerized microphone signals are transformed to the frequency domain and deconvolved with transfer functions to compensate for directivity functions. Numerical simulations, as well as experiments using rotating dipole loudspeakers, were conducted to verify the proposed method. It is demonstrated that the method is suitable for rotating sources with arbitrary orientation and works well under a high level of background noise. Positions and strengths of sources are estimated more accurately than traditional algorithms.

Acoustic spatial patterns recognition based on convolutional neural network and acoustic visualization.

In this work, a convolutional neural network (CNN) is applied to recognize acoustic spatial patterns with the aid of acoustic visualization. The acoustic spatial patterns are obtained by the singular value decomposition of an acoustic radiation operator built with the boundary integral equation. It is to explore the powerful capability of the CNN in the image processing by analogously rendering the measured acoustic spatial patterns into images. Due to practical limitations, a higher resolution of an acoustic image is achieved by interpolating the pressure on a coarse grid. Steady-state analysis of acoustic problems is a complex domain problem. The acoustic fields are then supplied into a CNN scheme as two-channel data which are real and imaginary components of the pressure. Random noises and incident waves with varying energy are added to the measured data to simulate influences from uncorrelated and correlated noises, respectively. It is demonstrated that once the CNN scheme is built and trained with adequate data, which is numerically synthesized, the patterns can be more accurately and robustly recognized by comparing it with the cross-correlation based methods. The hierarchical feature representative as well as nonlinear perception makes the proposed method a promising approach for fault diagnosis and condition monitoring based on spatial acoustic measurements.

A boundary element method based near field acoustic holography in noisy environments.

In noisy environments, the acoustic wave is complicated and consists of the radiated wave, the incident wave, as well as its scattering wave. Double-layered pressure measurement is introduced to the boundary element method based near field acoustic holography to recover the free field quantities. First, the incoming and outgoing propagation waves are separated by exploring the propagation property of the two waves from their source to the field with the boundary integral equation. Subsequently, the scattering wave is filtered out by considering the boundary condition of the vibrating structure. Further, a measurement on an enclosing hologram is adopted to accurately reconstruct the distribution of normal velocity on the boundary. Two sets of the system of linear equations are built on the double-layered measurements. The Schur complement equation is then applied in conjunction with the Tikhonov regularization method to obtain an optimized reconstruction. Numerical examples are set up for two representative radiators impinged by incident waves. It is demonstrated that the free field normal velocity can be correctly reconstructed even if the signal-to-noise ratio is negative. An experiment is conducted for the cubic radiator to verify the accuracy and potential for the practical reconstruction in a noisy environment.

A hybrid deconvolution approach to separate acoustic sources in multiple motion modes.

Motion mode is defined as a characteristic motion that a group of sources follow. If there are multiple groups of sources moving in the corresponding multiple motion modes, the beamforming map for a certain group of sources will be contaminated by the leakages from the other groups of sources. The original beamforming or deconvolution approaches fail to interpret the acoustic maps, as the source leakages may be mistaken for actual sources. A hybrid deconvolution approach is proposed to restrain the source leakages, so as to separate the acoustic sources in multiple motion modes. This approach simultaneously considers all the sources in the potential motion modes, and introduces equivalent sources in the corresponding motion modes to represent the sources. The equivalence between the actual sources and the equivalent sources leads to the construction of an expanded linear matrix equation. The sources in the respective motion modes are simultaneously extracted by solving the equation. The approach is shown effective by two numerical simulations and a practical experiment on two counter-rotating sources and one static source.

The effect of exposure duration on the subjective discomfort of aircraft cabin noise.

The time dependency for subjective responses to noise has been a controversial question over many years. For durations of up to 10 min, the discomfort produced by three levels of noise (ie 60, 70 and 80 dBA) was investigated in this experimental study to determine the relation of discomfort to the time duration of noise. The rate of increase in discomfort with increasing duration was 1.5 dB per doubling of exposure duration, whereas it is currently assumed to be 3 dB per doubling of exposure duration. The sound dose level (SDL) was proposed to predict the discomfort caused by noise of long duration. The combination of SDL and vibration dose value (VDV) provided more consistent estimates of the equivalent comfort contours between noise and vibration over durations from 2 to 32 s than the combination of sound exposure level and VDV or that of sound pressure level and r.m.s. acceleration. Practitioner Summary: The discomfort produced by noise of long duration can be well predicted from a new definition of sound dose level, where the discomfort increases at 1.5 dB per doubling of exposure duration.

Theoretical investigation of the effects of the cushion on reducing underwater noise from offshore pile driving.

Offshore pile driving noise has gained increasing attention due to its adverse influence on marine animals. Two models are established to investigate the influence of the cushion on the underwater noise from pile driving. A one-dimensional nonlinear finite difference model is developed to compute the impact force and the soil penetration. The radiated sound pressure is predicted by the second model based on a semi-analytical variational formulation. For the examined pile, a proper cushion can significantly dampen the high-frequency impact force and reduce the peak of the sound pressure. It is found that there exists a stiffness range within which the decline of the cushion stiffness effectively reduces the single sound exposure level but hardly increases the required hammer blows to achieve a certain penetration depth.

Reconstructing the normal velocities of acoustic sources in noisy environments using a rigid microphone array.

An acoustic source identification technique with single layer pressure measurement is presented to reconstruct normal velocities of target sources in noisy environments. The theory for this reconstruction is developed from the inverse patch transfer functions method which is supposed to combine measurements of pressure and velocity on a surface surrounding the source. The rigid microphone array is called an acoustic mask, which is designed to obtain pressure on the Neumann boundary condition and realized by microphones flush mounted on the aluminum plate. The validity of the proposed method is demonstrated by giving the normal velocities of two baffled loudspeakers in a noisy environment in the simulation and experiment. Another experiment of a clamped steel plate is further presented to illustrate the ability of the acoustic mask to obtain the partial velocity field of interest without reconstruction of the whole source surface velocity. The accuracy of this technique is demonstrated by comparison with the accelerometer method.

Malaria imported from Ghana by returning gold miners, China, 2013.

During May-August 2013, a malaria outbreak comprising 874 persons in Shanglin County, China, was detected among 4,052 persons returning from overseas. Ghana was the predominant destination country, and 92.3% of malarial infections occurred in gold miners. Preventive measures should be enhanced for persons in high-risk occupations traveling to malaria-endemic countries.

[Screening Radius of Active Case Detection and the Malaria Parasite Rate of Carriers in China-Myanmar Border].

OBJECTIVE: To explore the effective screening radii of active case detection of the 1-3-7 surveillance and response strategy, and investigate the malaria parasite rate of carriers in China-Myanmar border. METHODS: Three villages with indigenous malaria cases in Yingjiang County of Yunan Province were selected as study sites. The persons lived around the indigenous cases (index case) within the radius of 100 m, 300 m, 500 m, and 1 km were screened by microscopy and nested PCR. Parasite rate of asymptomatic carriers at different radii were calculated. RESULTS: Among 278 blood samples, the parasite rate of asymptomatic carriers was 1.1% (3/278) and 2.2% (6/278) using microscopy and nested PCR, respectively. Based on the results of nested PCR, all the asymptomatic carriers could be detected within a 300 m radius around the index case, and with the highest proportion (66.7%) in the radius of 101-300 m. CONCLUSION: The asymptomatic carriers of malaria parasites in the China-Myanmar border area can be effectively detected within a 300 m screening radius of index case by using nested PCR.

A method to compute the radiated sound power based on mapped acoustic radiation modes.

Application of modal expansion approach for the exterior acoustic field has drawn wide research interests in recent years. This is primarily due to the acoustic radiation modes (ARM) that can diagonalize the impedance matrix, hence significantly simplifying the computation of radiated sound power. The orthogonal ARM are typically calculated via a standard eigenvalue analysis of the impedance matrix, which normally leads to numerical difficulties especially for wideband frequency and large scale problems. In this paper, a theory of mapped ARM is proposed to avoid the cumbersome computation of ARM for convex structures. A mapping relationship between the ARM on the surface of an equivalent spherical source and the mapped ARM on the surface of a convex structure is obtained based on the equivalent source method, multipole expansion method, and boundary integral method. Furthermore, analytical expressions for the radiated sound power of structures vibrating in its mapped ARM as well as that of spheres are derived. Finally, a simple method is proposed to approximate the radiated sound power based on the modal decomposition method and the mapping relationship. Numerical simulations are conducted to validate the accuracy and efficiency of the proposed approach, and different vibrating structures with various geometries are considered. Results demonstrate that the proposed methodology for calculating the radiated sound power of convex structures is very efficient and accurate as compared with the traditional approach.

Modeling transient sound propagation over an absorbing plane by a half-space interpolated time-domain equivalent source method.

A half-space interpolated time-domain equivalent source method (ITDESM) is proposed to model the transient sound propagation over an absorbing plane. In this approach, a closed-form transient half-space Green's function (i.e., the impulse response function in three-dimensional space) for a pure absorbing infinite plane is introduced to develop the half-space ITDESM formulation. Instead of the free transient Green's function employed in the conventional ITDESM, such Green's function contains the reflection effect of the absorbing plane. As a numerical example, reconstructing the transient pressure fields from two monopole sources is depicted, where both monopoles are located in front of an infinite plane with absorbing impedance. Simulation results indicate that the half-space ITDESM can reconstruct the half-space transient sound fields in both the space and time domains very well. The proposed method is also investigated by taking into account the measurement noise in the reconstruction process. An experiment of an impacted steel plate above a glass wool board is presented to illustrate the validity of the proposed method under actual conditions.

Breaking the trade-off between capacity and stability in vanadium-based zinc-ion batteries.

Water in electrolytes is a double-edged sword in zinc-ion batteries (ZIBs). While it allows for proton insertion in the cathode, resulting in a significant increase in capacity compared to that of organic ZIBs, it also causes damage to electrodes, leading to performance degradation. To overcome the capacity-stability trade-off, organic solvents containing a small amount of water are proposed to mitigate the harmful effects of water while ensuring sufficient proton insertion. Remarkably, in a Zn(OTf)2 electrolyte using 8% H2O in acetonitrile as the solvent, Zn‖(NH4)0.5V2O5·0.5H2O exhibited a capacity as high as 490 mA h g-1 at a low current (0.3 A g-1), with a capacity retention of 80% even after 9000 cycles at high current (6 A g-1), simultaneously achieving the high capacity as in pure aqueous electrolytes and excellent stability as in organic electrolytes. We also found that the water content strongly impacts the kinetics and reversibility of ion insertion/extraction and zinc stripping/plating. Furthermore, compared to electrolytes with pure acetonitrile or H2O solvents, electrolytes with only 8% H2O in acetonitrile provide higher capacities at temperatures ranging from 0 to -50 °C. These discoveries enhance our understanding of the mechanisms involved in ZIBs and present a promising path toward enhancing electrolyte solutions for the creation of high-performance ZIBs.