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Deep learning has been widely applied to intelligent fault diagnosis of rotating machines. In particular, convolutional neural network (CNN) improves the accuracy of diagnosis due to automatic feature extraction ability. However, CNN cannot make full use of the temporal information of the input signals. In order to overcome the above weaknesses, a new depth diagnositic framework called two stream convolution neural network with temporal information(TITSCNN) is proposed for bearing fault diagnosis. First, we obtain tempory signal through the difference of data points in the input signal. Next, tempory signal and original signal are used as input of two CNN branches respectively. Then, an attention mechanism is used to aggregate the features and assign weights to the features extrated by CNN adaptively. Finally, the learned high-level representations are fed into full connect layer to perform fault diagnosis. Experiments are conducted and the results showed that TITSCNN has higher accuracy compared to state-of-the-art methods. Further, experimental results demonstrated that TITSCNN has excellent noise immunity and transformation performance.

Inspired by the traditional floating raft vibration suppression system, in order to solve the problem of random vibration of the plate, through miniaturizing the floating raft system and using the microfloating raft arrays to replace the distributed dynamic vibration absorbers, a plate with microfloating raft arrays is constructed in this paper. The vibration response equation of the structure under multi-point random excitation is established by using modal superposition method. The auto-power spectral density (APSD) of displacement is obtained by using MATLAB, and the influence of system parameters on the vibration response is analyzed. Optimal combination of parameters is obtained by the generalized pattern search algorithm. Vibration reduction effect of this structure is analyzed. The results show that redistribution of microfloating raft element interval and an increase in the thickness, flexural rigidity and damping of the plate could increase the vibration suppression effect. It is also shown that an increase in mass ratio and stiffness ratio of the microfloating raft element could significantly reduce the vibration of the plate. When it achieves the optimal vibration suppression effect, the mass ratio, the stiffness ratio and the damping ratio are 0.3, 8.8562 and 4.7660, respectively. Compared with other plate structures, the plate with microfloating raft arrays of optimal parameter has the minimum APSD of displacement and minimum energy.

The design of vigorous tools for creatinine determination is extremely important in the diagnosis and treatment of kidney diseases. In the study, we examine a robust fluorescent turn-on probe (NCP-Pd) for creatinine detection in a completely aqueous solution based on the metal palladium-catalyzed reaction. In the presence of creatinine, the NCP-Pd dissociates and subsequently restores the fluorescence due to elimination of the heavy atom quenching effect and prevention of the photoinduced electron transfer effect. The probe NCP-Pd displays excellent detecting performance with respect to creatinine such as good water solubility, high selectivity, and a low detection limit (0.16 μM). Additionally, in order to ensure its clinical application, this probe is operated in blood serum samples for detecting creatinine and compared with a commercial clinical method. The results indicate an extremely high agreement with the commercial clinical method. Furthermore, the results confirm that the probe NCP-Pd exhibits satisfactory cell permeability and low cytotoxicity and can detect creatinine in L929 and HCT116 cells. The study provides a potential application for detecting creatinine and conducting pathological research on creatinine-involved diseases.

This study describes the adsorption performance of a novel ethylenediamine rosin-based resin (EDAR) for several industrially-important phenolic compounds. Its removal of 4-nitrophenol (4-NP) from water was comparable to or better than many commercial resins, although it was less effective with other phenols (i. e., phenol, 2,4-dichlorophenol, 4-chlorophenol, and 4-methylphenol). Experimental conditions for batch adsorption of 4-NP by EDAR are evaluated, the adsorption kinetics is well described by the pseudo-second-order model (R2 > 0.99) and isotherm follows the Langmuir isotherm model (R2 > 0.99), with the maximum monolayer adsorption capacity of 82 mg g−1 at pH 6.0 and 293 K. The thermodynamic parameters indicate that the adsorption is spontaneous and endothermic. Also, quantum chemistry calculations indicate involvement of hydrogen-bonding between 4-NP and amino groups of EDAR. 4-NP was efficiently desorbed from the loaded EDAR resin by 0.2 M HCl, and the resin could be recycled with only a small decrease in its initial adsorption capacities. Thus, EDAR is a promising adsorbent for the removal of 4-NP during water treatment.

Resins derived from natural rosin have been described recently as environmentally-friendly adsorbents with potential uses in the clean-up of wastewaters and the treatment of drinking waters. However, in order to improve the design of these products it is important to understand the chemical mechanisms through which they act. We now describe the combined use of EPR spectroscopy and Cu(II) to probe directly the metal coordination environment after uptake by various rosin-derived products. Clear distinctions are demonstrated between the copper bonding in different adsorbent preparations. Furthermore, in the case of nitrogen cross-linked products, the spectral parameters also provide information on the number of nitrogen atoms in the immediate atomic environment of the copper atom when covalent bonding is involved. This methodology works well for adsorption from solutions containing multiple components, because only those that are paramagnetic are detected, and different types of paramagnetic metal ion produce distinctly different EPR spectra.

This paper presents an adaptive constraint control approach for Electronic Throttle Control System (ETCS) with asymmetric throttle angle constraints. The adaptive constraint control method, which is based on barrier Lyapunov function (BLF), is designed not only to track the desired throttle angle but also to guarantee no violation on the throttle angle constraints. An ETC mathematic model with complex non-linear system is considered and the asymmetric barrier Lyapunov function (ABLF) is introduced into the design of the controller. Based on Lyapunov stability theory, it can be concluded that the proposed controller can guarantee the stability of the whole system and uniformly converge the state error to track the desired throttle angle. The results of simulations show that the proposed controller can ensure that there is no violation on the throttle angle constraints.

As the fatigue life prediction of wire rope has the defects of large samples and many interference factors, this paper takes the 6×31WS+FC type wire rope as research carrier. Based on small samples, the grey particle filter method has been creatively proposed to realize the wire rope fatigue life prediction under various load conditions. First, combining the reliability life data prediction with the equivalent alternating stress of the dangerous part during the fatigue test, the reliability stress-life curve was determined. Subsequently, the particle filter method has been used to modify the curve to obtain the modified P-S-N curve. Finally, with theory of fatigue damage accumulation, the fatigue life prediction model was established, and compared with the test results. The results show that based on small sample conditions, the proposed method can predict the fatigue life of wire ropes under various loading conditions with high precision, which proves the general applicability.

Additional file 1.

Background: The outbreak of the novel coronavirus disease COVID-19 caused panic and psychological stress throughout the World. We investigated the extent of adverse psychological reactions in two medical staff groups in China, and explored the importance of online psychological assistance for them.Methods: A cross-sectional online survey including Hospital Anxiety and Depression Scale (HADS) and Insomnia Severity Index (ISI) was utilized to assess anxiety, depression, and insomnia. Propensity score matching (PSM) was applied to match sex and age between the two groups. Differences in the prevalence of adverse psychological reactions between the two groups were compared by a Chi-square test. A multivariate logistic regression analysis was utilized to search for associated adverse psychological reaction factors of two groups.Results: A total of 2,920 medical staff took part in the survey, including 470 frontline and 2,450 non-frontline medical staff. The risk of the frontline group experiencing anxiety, depression, insomnia-early, insomnia-middle, and insomnia-late were 1.16, 1.28, 1.26, 1.22, 1.28 times those of the non-frontline group after PSM. For frontline medical staff, the spinsterhood state (OR = 1.23, 95% CI: 1.00–1.51; P = 0.05) was a risk factor for anxiety. Bachelor or college degree (OR = 2.23, 95% CI: 1.24–4.02, P = 0.01) and a contact history with COVID-19 patients (OR = 1.62, 95% CI: 1.10–2.40; P = 0.02) were risk factors for insomnia. For non-frontline medical staff, being a woman (OR = 1.49, 95% CI: 1.08–2.06, P = 0.01) was a risk factor for anxiety, whilst being in a middle age group was a protective factor for anxiety (OR = 0.70, 95% CI: 0.50–0.99, P = 0.04) and depression (OR = 0.65, 95% CI: 0.45–0.93, P = 0.02). Being a woman (OR = 1.47, 95% CI: 1.14–1.89, P = 0.003) and working in a COVID-19 unit (OR = 1.31, 95% CI: 1.11–1.54, P = 0.001) were risk factors for insomnia, whilst the spinsterhood state (OR = 0.80, 95% CI: 0.67–0.95; P = 0.01) was a protective factor for insomnia. Online forms of psychological aid were all popular with medical staff.Conclusions: The prevalence of anxiety, depression, and insomnia in frontline medical staff was significantly higher than in the non-frontline group. Appropriate intervention methods should be adopted according to the different influencing factors of the two groups. Online psychological aid was the preferred mechanism for relieving psychological problems.

In this work, the feasibility of a novel sensitive electrochemiluminescence aptasensor for the detection of lysozyme using Ru(bpy)32+-Silica@Poly-L-lysine-Au (RuSiNPs@PLL-Au) nanocomposites labeling as an indicator was demonstrated. The substrate electrode of the aptasensor was prepared by depositing gold nanoparticles (AuNPs) on 3D graphene-modified electrode. The lysozyme binding aptamer (LBA) was attached to the 3D graphene/AuNPs electrode through gold-thiol affinity, hybridized with a complementary single-strand DNA (CDNA) of the lysozyme aptamer labeled by RuSiNPs@PLL-Au as an electrochemiluminescence intensity amplifier. Thanks to the synergistic amplification of the 3D graphene, the AuNPs and RuSiNPs@PLL-Au NPs linked to Ru(bpy)32+-ECL further enhanced the ECL intensity of the aptasensor. In presence of lysozyme, the CDNA segment of the self-assembled duplex was displaced by the lysozyme, resulting in decreased electrochemiluminescence signal. Under the optimized conditions, the decrease in electrochemiluminescence intensity varied proportionally with the logarithmic concentration of the lysozyme from 2.25 × 10-12 to 5.0 × 10-8 mol L-1, and the detection limit was estimated to 7.5 × 10-13 mol L-1. The aptasensor was further tested in real samples and found reliable for the detection of lysozyme, thus holding great potential application in food safety researches and bioassay analysis.

The surface forming mechanism is very important for material processing technology, which can directly influence the surface quality and processing efficiency. A new method for regulating and predicting the surface topography for ultrasonic vibration- assisted grinding (UAG) is presented in this paper. According to the kinematics analysis, the surface generating model is developed step by step in this study to control the surface micro structure and modify the machining parameters. The grinding force model and material removal rate model are also established for evaluating the UAG processing performance. Depend on the mathematical models, relationships between surface topography, grinding force, material removal rate, and ultrasonic vibration features can be revealed. Micro structure and high-precision surface can be design and manufactured through theoretical calculation. Due to the grain trajectory regulating, surface forming simulation was executed for verify the theory deduction. This model can be developing as a useful foundation for surface quality and machining efficiency improvement in UAG.

Factors that affect adsorption of a synthetic humic acid (HA) on a zeolite modified with the surfactant N,N-dimethyl dehydroabietylamine oxide (DAAO) (SMZ) were investigated in batch and fixed bed column experiments. Adsorption increased with increasing HA concentrations and contact time, but decreased with increasing pH, temperature, and ionic strength. Adsorption of HA on SMZ was increased by the presence of the cations Ca2+ and Mg2+, whereas anions such as NO3−, HCO3−, SO42−, and PO43− showed the opposite trend, and competed with HA adsorption. HA adsorption on SMZ was well-fitted by pseudo-second order kinetics, and described by the Langmuir isotherm model. The maximum adsorption capacity in batch experiments calculated from the Langmuir adsorption isotherm was about 126 mg g−1. Thermodynamic calculations showed that HA adsorption on the zeolite with bilayer DAAO coverage was spontaneous and exothermic. Optimum desorption was obtained using 0.1 M NaOH with a recovery of 94%. The HA adsorption capacity of SMZ at the breakthrough point was greatly influenced by bed depth, and could be described by the Thomas model. Adsorption mechanisms are interpreted as involving mainly hydrogen bonding and electrostatic interactions.

In the paper, on the basis of the stress field intensity method, the internal complex wingding structure of 6 × 31SW + FC type wire rope is analyzed and calculated. As a first step, considering the weakening speed of weight function in the stress field intensity method is too fast, a modification is presented to make it more suitable for the calculation of the fatigue life of wire rope. The load spectrum of the critical locations of wire rope is then established, based on the Costello mechanical model and the actual working conditions. Through the stress field intensity method, the time history curve of stress field is then obtained. Subsequently, the fatigue life of wire rope is calculated by using the linear cumulative damage theory of fatigue. The wire rope fatigue test rig is established, and the experimental value of the fatigue life of wire rope is compared with the theoretical calculation value. The results show that the experimental load of 90 t is the demarcation point of high and low cycle fatigue of wire rope, the theoretical values and the test results are close to each other in the fatigue cycle, which proves the effectiveness of the stress field intensity method in predicting the fatigue life of the wire rope.

Piezoelectric vibration energy harvesting technologies have attracted a lot of attention in recent decades, and the harvesters have been applied successfully in various fields, such as buildings, biomechanical and human motions. One important challenge is that the narrow frequency bandwidth of linear energy harvesting is inadequate to adapt the ambient vibrations, which are often random and broadband. Therefore, researchers have concentrated on developing efficient energy harvesters to realize broadband energy harvesting and improve energy-harvesting efficiency. Particularly, among these approaches, different types of energy harvesters adopting magnetic force have been designed with nonlinear characteristics for effective energy harvesting. This paper aims to review the main piezoelectric vibration energy harvesting technologies with magnetic coupling, and determine the potential benefits of magnetic force on energy-harvesting techniques. They are classified into five categories according to their different structural characteristics: monostable, bistable, multistable, magnetic plucking, and hybrid piezoelectric–electromagnetic energy harvesters. The operating principles and representative designs of each type are provided. Finally, a summary of practical applications is also shown. This review contributes to the widespread understanding of the role of magnetic force on piezoelectric vibration energy harvesting. It also provides a meaningful perspective on designing piezoelectric harvesters for improving energy-harvesting efficiency.

In order to specify proper tolerances in the product design process, the tolerance optimization model should be established properly and solved accurately. In this paper, several kinds of widely used manufacturing cost functions, including exponential function, reciprocal power function, and polynomial function, are considered simultaneously to calculate the manufacturing cost of different components. Then, the most suitable manufacturing cost function for each component is chosen so that the fitting error is minimized. After the manufacturing cost functions are determined, the tolerance optimization model is established to minimize the total cost including manufacturing cost and quality loss. In the tolerance optimization model, both assembly tolerance constraint and process accuracy constraints are considered. In order to solve the tolerance optimization model accurately, the Lagrange multiplier method is applied and closed-form solutions of optimal tolerances are established. The calculating results demonstrate that the proposed method has high accuracy.

Drug delivery systems are required to be safe, minimally invasive and effectively delivery drug to the target tissues. But delivery drugs to the eye has not yet satisfied this need. Here, we focused on examining the distribution of dexamethasone (DEX) in ocular and plasmic samples following controllable continuous sub-Tenon drug delivery (CCSDD) of dexamethasone disodium phosphate (DEXP) in rabbit, and to compare that with two traditional routes: subconjunctival injection and intravenous injection. The DEX concentration was analyzed by Shimadzu LC–MS 2010 system. In CCSDD group, during observed 24 h, the mean DEX level in collected samples from highest to lowest following in order: sclera, cornea, retina/choroid, iris, plasma, aqueous humor, lens and vitreous body. In ocular solid tissue, the DEX level in posterior segment is higher than in anatomic corresponding anterior segment, but it is opposite in ocular fluid tissue. High levels of DEX were maintained at 12 h in the ocular tissue immediately after the administration. Even at 24 h, the mean DEX concentration was 31.72 ng/ml and 22.40 ng/ml in aqueous and vitreous, respectively. In CCSDD group, the ocular DEX exposure (AUC0-24) is much higher and plasma exposure is much less than IV group, and it is also similar in SC group except iris. The amount of DEX levels are markedly increased in ocular tissues but it yield lower plasma levels indicating reduction of systemic absorption by CCSDD. Thus, CCSDD is an effective method of delivering DEX into anterior and posterior segment of the eye.

Corticosteroids have been used for treatment of posterior segment eye diseases, but the delivery of drug to the posterior segments is still a problem to resolve. In our study, we explore the feasibility of Sub-tenon’s Controllable Continuous Drug Delivery to ocular posterior segment. Controllable continuous sub-tenon drug delivery (CCSDD) system, intravenous injections (IV) and sub-conjunctival injections (SC) were used to deliver dexamethasone disodium phosphate (DEXP) in rabbits, the dexamethasone concentration was measured in the ocular posterior segment tissue by Shimadzu LC-MS 2010 system at different time points in 24 h after first dose injection. Levels of dexamethasone were significantly higher at 12, 24 h in CCSDD than two other approaches, and at 3, 6 h in CCSDD than IV in vitreous body (p

At present, the world economy is developing rapidly and product life cycle become more and more short. But the resources on the earth are limited, leading to the rapid decline of available resources. For these reasons, sustainable development has become an inevitable choice. As a sustainable strategy, remanufacturing has received the attention of many researchers and is widely adopted in the industry. In this paper, selective assembly for remanufacturing engine is researched. In most research about selective assembly, the number of groups is fixed. In this paper, the number of groups and the range of each group are changeable, and the assembly accuracy is improved efficiently.

This study investigated systematically the factors influencing the formation of iodinated disinfection by-products (I-DBPs) during chloramination of I--containing waters, including reaction time, NH2Cl dose, I- concentration, pH, natural organic matter (NOM) concentration, Br-/I- molar ratio, and water matrix. Among the I-DBPs detected, iodoform (CHI3), iodoacetic acid (IAA), diiodoacetic acid (DIAA), triiodoacetic acid (TIAA), and diiodoacetamide (DIAcAm) were the major species produced from reactions between reactive iodine species (HOI/I2) and NOM. A kinetic model involving the reactions of NH2Cl auto-decomposition, iodine species transformation and NOM consumption was developed, which could well describe NH2Cl decay and HOI/I2 evolution. Higher concentrations of CHI3, IAA, DIAA, TIAA, and DIAcAm were observed in chloramination than in chlorination, whereas IO3- was only formed significantly in chlorination. Maximum formation of I-DBPs occurred at pH 8.0, but acidic conditions favored the formation of iodinated haloacetic acids and DIAcAm. Increasing Br-/I- molar ratio from 1 to 10 did not increase the total amount of I-DBPs, but produced more bromine-substituting species. In addition, chloramination of 18 model compounds indicated that low-SUVA254 (specific ultraviolet absorbance at 254nm) NOM generally favored the formation of I-DBPs compared to high-SUVA254 NOM. Finally, potential pathways for I-DBPs formation from chloramination of NOM were proposed.

Syringe filters are widely used for sample pretreatments in laboratories. This study found that, surprisingly, these filters can leak dissolved organic carbon (DOC) that can potentially serve as precursors of disinfection by-products (DBPs). Nine common types of syringe filters were assessed. The results showed that the DOC of ultrapure water increased after syringe filtration. The DOC shed from filter membranes was characterized, whose spectra showed that the main compounds exhibited a low apparent molecular weight. Five classes of DBPs were investigated including trihalomethanes, haloacetaldehydes, haloacetonitriles, haloacetamides and halonitromethanes, among which trichloromethane (TCM), dichloroacetaldehyde (DCAL), trichloroacetaldehyde (TCAL), dichloroacetonitrile (DCAN), and trichloronitromethane (TCNM) were principally detected. The DBP formation was affected by chlorination time and membrane types. In general, the use of the poly vinylidene fluoride membrane resulted in the highest formation of TCM and TCAL, whereas nylon and mixed cellulose esters membranes contributed significantly to the formation of DCAN and TCNM, respectively. The shedding DOC and the formation of TCM, DCAL and TCAL from filter membranes were mitigated effectively by pre-washing; however, the contribution of membrane leakage to DCAN and TCNM formation was still notable, even with a pre-wash volume of 50 mL. When unwashed syringe filters were used for a real water sample, the DBP formation increased by up to 73.2% compared to the pre-washed ones; particularly for TCNM it was always over 15%. Therefore, for better quality control in laboratories, more attention should be paid to the syringe filters during sample pre-treatments, particularly when DBP formation is being investigated.

The pigments of sugarcane juice may be occluded within sugar crystals and impart a yellow or brown tint to sucrose, which causes a negative effect on the quality of white sugar. Adsorption is a useful method to remove color from sugarcane juice. In the present study, a novel rosin-based polymer@silica core–shell adsorbent (RP-Si-CA) bearing silica as a support, modified rosin as a cross-linking skeleton, and quaternary ammonium cations as a functional group was prepared and used as a decolorization agent for sugarcane juice. Synthetic melanoidin was used as a sugarcane juice colorant model to study the adsorption performance of RP-Si-CA. The equilibrium adsorption capacity of RP-Si-CA for melanoidins was 0.83 mg/g (experimental conditions: RP-Si-CA dosage, 0.30 g/mL; temperature, 333 K; pH, 7.0; initial melanoidin concentration, 270 mg/L), and the corresponding removal rate reached 92%. Studies on the kinetics, isotherms, thermodynamics, and interaction mechanisms of melanoidin adsorption by RP-Si-CA revealed that adsorption is mainly affected by chemisorption due to the interaction between the quaternary ammonium cations of RP-Si-CA and the carboxylate ions of the colorant. Moreover, adsorption occurred via an endothermic monolayer process and was spontaneous. Recycling experiments indicated that RP-Si-CA presents good regenerability.

Micro arc oxidation (MAO), as a new special surface treatment method, has been introduced to the marine antifouling field for titanium alloys because of the anatase and rutile TiO 2 with antibacterial effects obtained during the oxidation process. Despite this, metallic oxide antifouling additives have been added into MAO coatings to improve the antibacterial and antifouling abilities of titanium alloy. In this study, MAO coatings containing nanometer particles were obtained by adding nano Cu 2 O and nano ZnO into the electrolyte. Structure, morphology, phase constitution and chemical composition of the MAO coating film were studied by SEM, XRD and EDS. The antibacterial properties of the film were evaluated by exposing the specimens to Escherichia coli and comparing the Ti-MAO and Ti-bared controls. The results showed that the MAO process on Ti6Al4V has an outstanding antibacterial property which can be further enhanced by nano Cu 2 O and nano ZnO. The Ti-MAO–Cu 2 O group had the best antibacterial ability. These findings indicate that by means of this process adding nanometer metallic oxide into an MAO coating film via an electrolyte is useful for enhancing the antibacterial and antifouling abilities of titanium.

The fatigue life prediction of wire rope has the characteristics of large sample size required and many uncertain factors. In this paper, the 40 6 × 31SW FC type wire rope is taken as the research object. Under the condition of fatigue life data of small sample size, the fatigue life prediction of wire rope under different load conditions is realized based on gray theory. As a first step, for the problems existing in the current fatigue life prediction of wire rope, this paper constructs an improved GM (1,1) model and predicts the reliability life data of wire rope under small sample size condition. Subsequently, based on this, combined with the equivalent alternating stress of the critical locations of wire rope during the fatigue test, the reliability stress-life curve of the critical locations of wire rope is determined; Finally, the fatigue life prediction model of wire rope is obtained by combining with the cumulative damage theory of fatigue. The fatigue life of wire rope under different loads is predicted and compared with the experimental value. The results show that the proposed method has high accuracy in predicting the small sample fatigue life of wire rope under single and combined loading conditions, which proves the effectiveness of this method.

In order to improve energy harvesting efficiency, this paper shows the design of a two-degree-of-freedom (2-DOF) nonlinear piezoelectric energy harvester. The proposed harvest is realized by introducing magnetic attraction to a 2-DOF piezoelectric cantilever beam in order to broaden the energy harvesting bandwidth. Electromechanical equations describing this nonlinear system are presented. The simulation results confirmed the advantage of this new 2-DOF nonlinear harvester. Performance comparison shows that the 2-DOF nonlinear harvester has much higher energy harvesting efficiency than a conventional one-degree-of-freedom (1-DOF) nonlinear one.

Factors that affect adsorption of a synthetic humic acid (HA) on a zeolite modified with the surfactant

Due to the effect of various factors, the product quality characteristics are sometimes non-normal distribution. In this paper, two most commonly used non-normal distributions, triangular distribution and trapezoidal distribution, are studied based on asymmetric quadratic quality loss. With asymmetric quality loss, it is necessary to optimize the process mean in order to reduce the expected quality losses. In order to optimize the process mean of the triangular distribution, the different distances between the target value and the process mean are considered, and two mathematical models are proposed to calculate the expected quality loss. Because the probability density function of the trapezoidal distribution is a three-segment function, in order to optimize the process mean of the trapezoidal distribution, three models are established. Solving the proposed models, analytical solutions for the optimal process mean are obtained, and equations for the minimum quality loss are established. Considering the sum of manufacturing cost and the minimum quality loss as the objective function, tolerance model is established to calculate the optimal tolerances. Therefore, the optimal process mean and optimal tolerances are obtained for triangular distribution and trapezoidal distribution. At last, an example is used to illustrate the validity of the established model.

Piezoelectric thin rings are periodically introduced and placed on a base plate along the radial direction, forming a one-dimensional thin circular plate of piezoelectric radial phononic crystals (CPPRPC). Based on flexural wave equation of thin circular plate and the transfer matrix method, the behavior of flexural waves propagating in CPPRPC is analyzed theoretically and numerically, especially in the band gaps. The transmission curves of CPPRPC and homogeneous-material plate are calculated for comparison. Afterwards finite element simulations are carried out to verify the theoretical results. Furthermore, the effects of the length ratio, thickness ratio, period number and control gain on the flexural wave band gap are discussed in detail. Our results show that there are band gaps of flexural wave in CPPRPC. Structural parameters and outer active control gain have important influences on the band gaps. In particular, low and broad band gaps can be obtained effectively by varying outer active control gain.

A novel N , N -dimethyl dehydroabietylamine oxide (DAAO) surfactant was synthesized via alkylation and oxidation of dehydroabietylamine. A series of surfactant-modified zeolites (SMZs) with different loadings of DAAO were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, N 2 adsorption, and elemental and thermogravimetric analyses. The adsorptive removal of an anionic dye, Congo red (CR), from aqueous solution was then investigated as a function of surfactant loading, initial dye concentration, pH, and ionic strength. The adsorption capacity of CR on SMZ increased with an increase in DAAO loading or initial dye concentration, but decreased with an increase in pH or ionic strength. The Langmuir isotherm model fits well with the equilibrium adsorption isotherm data and its calculated maximum monolayer adsorption capacity was 69.94 (mg/g) at pH 6.0, 20 °C. The results showed that the CR adsorption was best described by pseudo-second-order kinetics. The calculated thermodynamic parameters indicated that CR adsorption onto SMZs was spontaneous and exothermic, and the possible mechanisms controlling CR adsorption on the SMZ included hydrogen bonding, electrostatic interactions, and hydrophobic interaction.

Rosin derived from conifer trees is used as the basis for a novel environmentally-friendly adsorbent prepared from a sustainable resource. After treatment with ethylenediamine, ethylenediamine rosin-based resin (EDAR) is produced, which possesses cation exchange capacity that is comparable to that of the best commercial synthetic resins. This is demonstrated by its application to the removal of Pb, Cd, and Cu from water, in single and multicomponent systems. Maximum uptake was obtained at pH 5 and in the order Pb(II) &gt, Cd(II) &gt, Cu(II). The maximum adsorption of Pb was ~1.8 mmol/g, but the adsorption process resembled the Freundlich isotherm, whereas the adsorption of Cd(II) and Cu(II) followed the Langmuir isotherm. In the multicomponent systems, there was direct competition between Pb and Cd for sorption sites, whereas the results with Cu indicated it had a preference for different types of sites compared to Pb and Cd. The EDAR resin could be efficiently regenerated and used repeatedly with only a small decrease in performance. Characterization of EDAR, and investigations of its adsorption mechanisms using physical, spectroscopic, and theoretical techniques, including fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (13C NMR), scanning electron microscope (SEM), Brunauer Emmett Teller (BET) method, elemental analysis, thermogravimetric analysis (TGA), and molecular dynamics calculations, showed that amino groups have a critical role in determining the cation adsorption properties. We conclude that this new adsorbent derived from an abundant natural material has the potential to make valuable contributions to the routine removal of heavy metal ions (HMs) from drinking water and wastewater.

Component tolerances have important influence on the cost and performance of products. In order to obtain suitable component tolerances, multi-objective tolerance optimization model is studied, in which the combined polynomial and exponential functions are used to model manufacturing cost. In this paper, analytical methods are proposed to solve the multi-objective optimization model. In this model, the objective function is not a monotone function, and it is possible that the assembly tolerance constraint, including worst-case method and root sum square method, is inactive. Therefore, two closed-form solutions are proposed for each component tolerance in terms of the Lambert W function. When the assembly tolerance constraint is not considered, the component tolerances are obtained and named as the initial closed-form solutions. If the initial solutions satisfy assembly tolerance constraint, it is the final value of optimal tolerances. Otherwise, constrained optimization model is established and Lagrange multiplier method is applied to obtain the new closed-form solution of component tolerances as the final value of optimal tolerances. Several simulation examples are used to demonstrate the proposed method.

Molecular acidity is an important physiochemical property essential in many fields of molecular studies, but an efficient and reliable computational approach to make accurate predictions is still missing. In this work, based on our previous studies to use gas phase electronic properties such as molecular electrostatic potential and valence natural atomic orbitals of the acidic atom and leaving proton, we demonstrate here that different approaches can be employed to tackle this problem. To that end, we employ 196 singly, doubly, and triply substituted benzoic acids for the study. We show that two different approaches are possible, one focusing on the carboxyl group through its localized electronic properties and the other on the substituting groups via Hammett constants and their additivity rule. Our present results clearly exhibit that with the linear models built from the singly substituted species, one can accurately predict the pK(a) values for the doubly and triply substituted species with both of these two approaches. The predictions from these approaches are consistent with each other and agree well with the experimental data. These intrinsically different approaches are the two manifestations of the same molecular acidity property, both valid and complementary to each other.