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Acoustic manipulation is a non-contact process that applies acoustic waves to immobilize particles into a specific region for a variety of potential applications. This provides an alternative way to address air ventilation requirements where building systems are becoming smarter and more efficient. Development of such a process within confined spaces can incorporate microscopic interactions to filter aerosol-based particulate matter (PM). In real-engineering conditions, it is hard to filter sub-micron particles (0.25–1.0 μm) than super-micron particles (> 2.5 μm) by using low-grade filters. The objectives of this work are twofold. First, we propose a new acoustic-driven pre-filtering device (i.e., a U-shaped resonant acoustic chamber) that can improve the working efficiency of low-grade filters for capturing such particles. Second, the device can optimize spatial homogeneity to enhance the removal efficiency of airborne particles under lower sound intensity requirements. The U-shaped acoustic-driven device in the form of a resonant chamber allows PM to reside at the pressure node of a standing wave. Experimental studies are conducted to verify the present design. The results show that an overall filtration efficiency of up to 89% for 1.0-μm airborne particles can be achieved when the acoustic-driven device is coupled together with a low-grade MERV-6 coarse filter. As a standalone device, the acoustic effect works well for the sub-micron particles with a filtration efficiency of up to 61% under a lower sound pressure level (116 dB) than as previously reported in the literature. In the analysis, we also discuss the performance dependence on frequency, sound pressure level and flow rate in terms of particle size distribution. The relevance of this research is a major step towards engineering an acoustic-based pre-filtering technique for developing future innovative ventilation solutions. [Display omitted] • A novel U-shaped acoustic-driven pre-filtering device in a ventilation duct is proposed. • The device can promote the filtration rate of the sub-micron particles (0.3–1.0 μm). • The device can operate at a far lower SPL (116 dB) than those reported in the literature. • Coupling with MERV-6 filters, a filtration efficiency of 89% for 1.0-μm particles is resulted. • The potential application of this work can maintain good air quality in indoor environments. [ABSTRACT FROM AUTHOR]

Studies the static structure factor of a suspension of charge-stabilized colloids. Mean spherical approximation; Primitive model for finite-size ions; Mode coupling theory for a colloidal dispersion; Application to the liquid-glass transition phase diagram; Effective one component model; Application to tetramethylammonia dodecyl-sulfate.

Abstract An atomistic-continuum multiscale approach is used to simulate the nonlinear dynamic behavior of simply-supported single layer graphene sheets subject to a uniformly distributed out-of-plane load. The dynamic equation of motion is derived and solved by the Newmark- β method. The evolution of surface morphology and the nonlinear effects in terms of geometrical and material nonlinearities can be captured by iteratively updating the system stiffness. It is found that the natural frequencies of simply-supported graphene sheets almost remain constant when the external load is in a small range. The present solutions are in good agreement with those results obtained from the linear vibration analysis by a semi-analytical method. As the applied load increases continuously, this gives rise to an elongation of graphene to increase the natural frequency. Based on the numerical approach, the surface morphology evolution of graphene can be visualized and explored. [ABSTRACT FROM AUTHOR]

Highlights • Vibration of nano-rods, nano-beams and nano-plates due to their structural characteristics is investigated. • The existence of an upper limit of the nonlocal scale parameter is presented and discussed. • The results are compared with the existing literature to confirm its validity. • The present work provides a basis for the choice of a nonlocal scale range for nano-materials/structures. Abstract Nonlocal elasticity theory is one of the most popular theoretical approaches to investigate the intrinsic scale effect of nano-materials/structures. The coupling of an internal characteristic length and a material parameter can be regarded as a nonlocal scale parameter in nano-meters. The range of this non-dimensional scale parameter is from zero up to different values previously. There is no doubt that the zero nonlocal scale parameter corresponds to a situation without any nonlocal effect. However, the determination of a peak value for the scale parameter is still uncertain. In fact, we frequently ask a simple but unresolved question, i.e., how strong is the nonlocal scale effect? This question is equivalent to what the maximum value of the nonlocal scale parameter is, since it was introduced to characterize the scale effect theoretically. Until now, various maximum values have been selected without rigorous verifications. In this paper, the nano-structural dependence of nonlocal dynamical behavior is investigated to present the existence of an upper limit for the scale parameter. Through three typical examples, the size-dependent behavior of nonlocal dynamics for various nano-structures is analyzed. The upper limit of the scale parameter can be determined accordingly. It is shown that an interval for the scale parameter in the illustrative examples can be found on the basis of the nonlocal softening physical mechanism, in which the equivalent stiffness of nano-structures is weakened than that predicted by the classical continuum theory. The present study contributes to a fuzzy zone in nonlocal elasticity where people are puzzled over the question how to select the upper limit of the nonlocal scale parameter. It is not only beneficial to the refinement of the nonlocal theory of elasticity, and also useful for the exploration of similar theories in nano-mechanics. [ABSTRACT FROM AUTHOR]

Highlights • A Rayleigh wave model in fluid saturated porous materials based on a nonlocal Biot theory is proposed. • The nonlocal parameter does not have significant influence on the energy distribution and most of the Rayleigh wave energy is contributed by the shear wave. • The influence of nonlocal parameters on the loss angle is examined. • The displacement fields induced by the Rayleigh wave for various frequencies are also investigated. • The attenuation of the displacement amplitude is strengthened by an increasing nonlocal parameter. Abstract In this paper, a Rayleigh wave model in fluid saturated porous materials based on a nonlocal Biot theory is proposed. The general characteristic equations expressed in terms of the Rayleigh wavenumbers are obtained. A specific fluid saturated porous material is used for numerical analysis. The present study shows that the nonlocal parameter does not have significant influence on the characteristics of Rayleigh waves within a low frequency range when comparing with the prediction of using the classical Biot theory. However, the influence of the nonlocal scale effect on the Rayleigh wave velocity and the displacement field becomes stronger as the response frequency increases. When the frequency exceeds a critical value, the Rayleigh wave velocity exhibits a negative dispersion. The displacement fields induced by the Rayleigh wave propagating in porous materials are also presented. An interesting phenomenon of the displacement fields is observed that the major axis of the displacement field ellipse will have a contra-rotation with respect to the vertical direction with increasing depth. This is different from the classical prediction in homogeneous materials. The presence of the nonlocal scale effect can also change the geometry property of displacement fields. In addition, the amplitude of the vertical displacement is attenuated along the depth, while the increment of the nonlocal parameters can strengthen the attenuation. Graphical abstract Image, graphical abstract Percentage contribution from the wave energy of the fast, slow and shear waves in the displacement u z for the nonlocal parameter τ = 0.005 m. [ABSTRACT FROM AUTHOR]

Controllable wrinkles in terms of amplitude, wavenumber and onset torsional angle are realized by using a twisting way of circular graphene sheets. A parametric study is carried out to investigate several factors, i.e., graphene size (inner radius r I and outer radius R o ) and torsional angle, on the wrinkle formation of graphene. The effects of both wavenumber and amplitude are investigated in detail, because they are the most critical parameters in tuning the surface morphology that is finally reflected on the electrical properties of graphene. It is found that the onset torsional angle on the formation of wrinkles decreases as the graphene size increases. When the torsional angle increases continuously, the amplitude will abruptly jump due to a sudden change in the wrinkle pattern. The wrinkle wavenumber of graphene can also be controlled by changing the ratio of the inner and outer radii (i.e., r I ∕ R o ). The variation of the strain energy shows that the structural transformation is reversible, this is mainly caused by the superelastic property of graphene. Hence, the formation of recyclable wrinkles can be realized by loading and unloading processes. [ABSTRACT FROM AUTHOR]

Three two-dimensional (2D) refined models are devised for the analysis of orthotropic thin plates with part-through surface and internal cracks under in-plane forces due to temperature differences. The refined models are used to formulate the governing equations for cracked orthotropic thin plates in a thermal environment. Subsequently, the refined models and their ensuing modified forms can be directly applied to all-over and finite-length cracks, respectively. Using an interface-fitted numerical scheme (i.e., matched interface and boundary technique), the resulting equations of motion for the buckling and free vibration of cracked orthotropic thin plates are solved. The effects of various crack types and dimensions on the critical buckling temperatures and vibration frequencies of orthotropic thin plates are investigated. The present models are also validated by comparing their numerical results with the line-spring model and three-dimensional finite-element solutions. Illustrative examples, including boron fiber/epoxy and glass-fibre-reinforced composite materials, are considered to show the superiority of the proposed models over the conventional one, especially in terms of understanding the effect of in-plane forces arising from temperature differences at the cracked location. • The effect of in-plane forces due to the rise of temperature at the crack location is investigated. • Refined crack models are proposed for the reduction of the bending stiffness due to the presence of in-plane thermal forces. • The critical buckling temperatures and frequencies of orthotropic cracked plates will decrease as the crack depth increases. • The surface and internal part-through cracks can be dealt with by the refined models effectively. [ABSTRACT FROM AUTHOR]

The semi-grand canonical ensemble theory augmented by the free volume approximation and the scaled particle theory was applied to construct the Helmholtz free energy density function f of a mixture of uncharged colloidal hard spheres and a depletion agent of colloidal hard platelets. The episode of the phase-separation phenomenon is then described by a composite f m which is written as a sum of the coexisting free energy densities f i ( i = gas, liquid or solid) and the latter is weighted by V i / V , V i and V being the i th spatial volume and total volume, respectively. In this work, we applied the free energy density minimization method to f m [16] and calculated the domains of phases in coexistence instead of delineating coexisting phase-diagram boundaries obtained by computing the pressure and chemical potential in the conventional thermodynamic equilibrium condition. The calculated coexistence domains thus have the same patterns as many colloidal laboratory experiments. We obtained in our calculated platelet–colloid phase diagram the well-known triangular area of triple-phases coexistence. This area, however, has to be realized as some kind of a kinetic process showing coalescence of two sets of coexisting biphases whenever any set of initial input number concentrations of platelets and colloids that falls inside this triangular area. In this kinetic phase-transition process, we find the triple phases of the platelet–colloid system always residing at the same three vertices of the triangle, but their spatial volumes are generally different depending on the initial number concentrations of platelets and colloids. It would be interesting and, a challenge as well, if laboratory experiments at the same quantitative level as that previously reported for the polymer–colloidal mixtures [7] can be carried out to confirm our theoretical findings. [ABSTRACT FROM AUTHOR]

An alternative method of deriving accurate and simple analytical approximate solutions to a structural dynamical system governed by a pair of strong irrational restoring forces is presented. This system can be used to represent mathematical models in various engineering problems. Prior to solving the problem, a rational approximation of the nonlinear restoring force function is applied to achieve a convergent truncation. Analytical solutions are then obtained using the combination of the harmonic balance method and Newton's method. This approach shows that lower-order analytical procedures can yield highly accurate and exact solutions that are difficult to obtain with an analytical expression. [ABSTRACT FROM AUTHOR]

We present first-principles theoretical calculations of the magnetic properties of bimetallic clusters Ag–Cu. The calculations proceeded by combining a previously developed state-of-the-art optimization algorithm (P.J. Hsu, S.K. Lai, J. Chem. Phys. 124 (2006) 0447110) with an empirical potential and applied this numerical scheme to determine first the lowest energy structures of pure clusters Ag 38 and Cu 38 , and also their different atomic compositions Ag n Cu 38 −n for n =1,2,…,37. Then, we carried out the Kohn–Sham spin unrestricted density functional theory calculations on the optimized atomic structures obtained in the preceding step. Given the minimized structures from the first step as input configurations, the results of these re-optimized structures by full density functional theory calculations yield more refined electronic and atomic structures. A thorough comparison of the structural differences between these two sets of atomic geometries, one from using an empirical potential in which the electronic degrees of freedom were included approximately and another from subsequent minimization using the spin unrestricted density functional theory, sheds light on how the electronic charges disperse near atoms in clusters Ag n Cu 38− n , and hence the distributions of electronic spin and charge densities at re-optimized sites of the cluster. These data of the electronic dispersion and the ionic configuration give clue to the mystery of the unexpected net magnetic moments which were found in some of the clusters Ag n Cu 38 −n at n =1–4, 24 as well as the two pure clusters. Possible origins for this unanticipated magnetism were explained in the context of the point group theory in much the same idea as the Clemenger–Nilsson model applied to simple metal clusters except that we draw particular attention to the atomic topologies and stress the bearing that they have on valence electrons in inducing them to disperse and occupy different molecular orbital energy levels. [ABSTRACT FROM AUTHOR]

Abstract: The present work derives the accurate analytical solutions for large amplitude vibration of thin functionally graded beams. In accordance with the Euler–Bernoulli beam theory and the von Kármán type geometric non-linearity, the second-order ordinary differential equation having odd and even non-linearities can be formulated through Hamilton''s principle and Galerkin''s procedure. This ordinary differential equation governs the non-linear vibration of functionally graded beams with different boundary constraints. Building on the original non-linear equation, two new non-linear equations with odd non-linearity are to be constructed. Employing a generalised Senator–Bapat perturbation technique as an ingenious tool, two newly formulated non-linear equations can be solved analytically. By selecting the appropriate piecewise approximate solutions from such two new non-linear equations, the analytical approximate solutions of the original non-linear problem are established. The present solutions are directly compared to the exact solutions and the available results in the open literature. Besides, some examples are selected to confirm the accuracy and correctness of the current approach. The effects of boundary conditions and vibration amplitudes on the non-linear frequencies are also discussed. [Copyright &y& Elsevier]

Abstract: This paper generalizes the newly developed DSC-Element method for free vibration analysis of skew plates using the first-order shear deformable plate theory. Basically, the DSC-Element method not only embraces the discrete singular convolution (DSC) delta type wavelet kernel as a trial function with the Ritz principle, but also incorporates the concept of the finite element method. The current approach is novel and flexible as contrast to the global numerical methods in treating the complex kinematic supporting edges. The objective of this paper is to examine the efficiency and validity of the DSC-Element method for oblique plates having large skew angles. Parametric studies for the vibration analysis of skew plates with various skew angles, thickness ratios, aspect ratios and continuous or discontinuous periphery supports are presented as well. The natural frequencies are directly compared and discussed with those reported in the open literature. Some frequency solutions for skew plates with mixed edge conditions are also presented. [Copyright &y& Elsevier]

Abstract: This paper deals with large amplitude oscillation of a nonlinear pendulum attached to a rotating structure. By coupling of the well-known Maclaurin series expansion and orthogonal Chebyshev polynomials, the governing differential equation with sinusoidal nonlinearity can be reduced to form a cubic-quintic Duffing equation. The resulting Duffing type temporal problem is solved by an analytic iteration approach. Two approximate formulas for the frequency (period) and the periodic solution are established for small as well as large amplitudes of motion. Illustrative examples are selected and compared to those analytical and exact solutions to substantiate the accuracy and correctness of the approximate analytical approach. [Copyright &y& Elsevier]

Abstract: This paper presents an alternative approach for mathematical modeling of an oscillating system with an irrational restoring force. Such a model corresponds to the oscillation of an elastic wire or string. A generalized Senator–Bapat perturbation technique is employed to deal with this nonlinear system. Unlike the conventional perturbation method, it not only solves the nonlinear problem without the requirement of small parameters, but also provides highly accurate solutions for small as well as large amplitudes of motion. Illustrative examples are selected and demonstrated for verifying the accuracy of this approach. [Copyright &y& Elsevier]

Abstract: Based on Mindlin''s first-order shear deformable plate theory, a DSC-Ritz element method is developed for the free vibration analysis of moderately thick rectangular plates with mixed supporting edges. The rationale of the present approach is not only to apply the discrete singular convolution (DSC) delta type wavelet kernel as a trial function with the Ritz method, but also to incorporate the method in finite elements in order to handle the mixed boundary constraints. The approach is novel and flexible as it passes through a bottleneck of the global DSC-Ritz method in treating the kinematic supporting edges with assorted discontinuities. A series of numerical simulations for rectangular Mindlin plates with various edge support discontinuities, plate thicknesses and aspect ratios are presented. For verification, the vibration frequencies thus established are directly compared with those reported in the open literature. New sets of numerical results for several other cases of moderately thick plates with mixed simply supported, clamped and free edges are presented and discussed in detail. [Copyright &y& Elsevier]

Abstract: A novel DSC-element method is proposed to investigate the free vibration of moderately thick plates based on the well-known Mindlin first-order shear deformation plate theory. The development of the present approach not only employs the concept of finite element method, but also implements the discrete singular convolution (DSC) delta type wavelet kernel for the transverse vibration analysis. This numerical algorithm is allowed dividing the domain of Mindlin plates into a number of small discrete rectangular elements. As compared with the global numerical techniques i.e. the DSC–Ritz method, the flexibility is increased to treat complex boundary constraints. For validation, a series of numerical experiments for different meshes of Mindlin plates with assorted combinations of edge supports, plate thickness and aspect ratios is carried out. The established natural frequencies are directly compared and discussed with those reported by using the finite element and other numerical and analytical methods from the open literature. [Copyright &y& Elsevier]

Abstract: This paper presents a new approach for solving accurate approximate analytical higher-order solutions for strong nonlinear Duffing oscillators with cubic–quintic nonlinear restoring force. The system is conservative and with odd nonlinearity. The new approach couples Newton’s method with harmonic balancing. Unlike the classical harmonic balance method, accurate analytical approximate solutions are possible because linearization of the governing differential equation by Newton’s method is conducted prior to harmonic balancing. The approach yields simple linear algebraic equations instead of nonlinear algebraic equations without analytical solution. Using the approach, accurate higher-order approximate analytical expressions for period and periodic solution are established. These approximate solutions are valid for small as well as large amplitudes of oscillation. In addition, it is not restricted to the presence of a small parameter such as in the classical perturbation method. Illustrative examples are presented to verify accuracy and explicitness of the approximate solutions. The effect of strong quintic nonlinearity on accuracy as compared to cubic nonlinearity is also discussed. [Copyright &y& Elsevier]

Abstract: A new harmonic balance approach for solving the large amplitude nonlinear vibration of a constant-tension string is introduced. The coupling of Newton's method with harmonic balancing takes the advantage of reducing the deficiency and complexity of the classical harmonic balance method in dealing with the nonlinear systems. The solutions are directly induced from a set of linear algebraic equations instead of a set of complicated, coupled nonlinear algebraic equations. Illustrative examples are selected and compared to some published data to verify the accuracy of the higher-order solutions. [Copyright &y& Elsevier]

Abstract: This paper deals with free vibration of a nonlinear system having combined linear and nonlinear springs in series. The conservative oscillation system is formulated as a nonlinear ordinary differential equation having linear and nonlinear stiffness components. The governing equation is linearized and associated with the harmonic balance method to establish new and accurate higher-order analytical approximate solutions. Unlike the perturbation method which is restricted to nonlinear conservative systems with a small perturbed parameter and also unlike the classical harmonic balance method which results in a complicated set of algebraic equations, the new approach yields simple approximate analytical expressions valid for small as well as large amplitudes of oscillation. Some examples are solved and compared with numerical integration solutions and published results. New solutions to the nonlinear systems are also presented and discussed. [Copyright &y& Elsevier]

Abstract: We propose a novel approach to calculate the thermodynamic phase diagrams. Differing from the conventional method in which the boundaries of the coexisting phases are the ultimate goal, the present work crosshatches the domains of the homogeneous phase and also the phases in coexistence. This was done by treating the separated phases as a composite system whose Helmholtz free energy density is expressed as the sum average of the constituent free energy densities which are weighed by their respective volume proportions. As a result, both the domains of the coexisting phases and the homogeneous single phase can be determined in addition to locating the phase boundaries, customarily obtained by imposing the thermodynamic equilibrium conditions of equal pressure and equal chemical potential. We illustrate the elegance of the theory by studying a thermally responsive microgel system. [Copyright &y& Elsevier]

Abstract: Although the existence of 13-atom icosahedral clusters in one-component close-packed undercooled liquids was predicted more than half a century ago by Frank, the existence of such icosahedral clusters is less clear in liquid alloys. We study the lowest-energy structures of 13-atom A x B13−x Lennard–Jones binary clusters using the modified space-fixed genetic algorithm and the artificial Lennard–Jones potential designed by Kob and Andersen. Curiously, the lowest-energy structures are non-icosahedral for almost all compositions. The role played by the icosahedral cluster in a binary glass is questionable. [Copyright &y& Elsevier]

Abstract: This Letter deals with a research subject in nonlinear mechanics and applied mathematics. It develops (i) accurate higher-order approximate analytical nonlinear oscillator system with negative dissipation, and (ii) analogy to long Josephson junction. Particular emphasis has been placed on the weakly damped nonlinear oscillating system with negative dissipation with respect to a transformed temporal variable derived from the weak link of the simplified Josephson junction model. Nevertheless, the system response is shown to be stable with positive dissipation with respect to the physical time at a specific location. The analysis forms an innovative extension of the harmonic balancing method commonly used in nonlinear oscillation and vibration systems such as the Duffing oscillator and van der Pol oscillator. Besides introducing coupling of linearized governing equation and harmonic balancing method, the method of averaging is also employed to obtain accurate higher-order analytical approximate solutions. Unlike the classical harmonic balance method without analytical solution, the approach not only considers energy dissipation but also presents simple linear algebraic approximate solutions. In addition, general approximate analytical expressions for the dispersion relations are also established. The presence of a small perturbed parameter is not required. [Copyright &y& Elsevier]

Abstract: Recent experimental studies [Z. Wu, B. Zhou, Z.B. Hu, Phys. Rev. Lett. 90 (2003) 048304] on an uncharged aqueous poly-N-isopropylacrylamide (PNIPAM) dispersion have shown that this microgel system is sensitive to temperature. This system was also experimentally found to be modeled quite well by microgel particles interacting via a hard-sphere repulsive plus an inverse power (temperature-dependent) attractive potential. To understand theoretically this thermally responsive PNIPAM dispersion, we apply a novel approach [G.F. Wang, S.K. Lai, Phys. Rev. E 70 (2004) 051402] to calculate its thermodynamic phase diagram. Differing from the conventional method in which the boundaries of the coexisting phases are the ultimate target, the present work places emphasis on crosshatching colloidal domains which include the homogeneous phase (gas, liquid or solid), two coexisting phases and perhaps also multi-phases in coexistence. Strategically, this was done by treating the coexisting phases as one composite system whose Helmholtz free energy density is written as the sum of constituent free energy densities each of which is weighed by its respective volume proportion. We show here that by minimizing the composite system''s free energy density the phase-diagram domains can all be determined in addition to the phase boundaries customarily obtained by imposing the conditions of equal pressure and equal chemical potential. Also, we present the theoretically predicted phase diagram of PNIPAM dispersion and compare it with the one observed experimentally. [Copyright &y& Elsevier]

Abstract: In general, this paper deals with general nonlinear oscillations of a nonconservative and single degree-of-freedom system with odd nonlinearity and, in particular, it presents accurate higher-order analytical approximate solutions to van der Pol damped nonlinear oscillators having odd nonlinearity and the Rayleigh equation. By combining the linearization of the governing equation with harmonic balancing and the method of averaging, we establish accurate analytical approximate solutions for the general weakly damped nonlinear systems. Unlike the classical harmonic balance method, simple linear algebraic equations instead of nonlinear algebraic equations are obtained upon linearization prior to harmonic balancing. The combination of these two methods results in very accurate transient response of the periodic solution. In addition and for the first time, this paper also presents a method for deducing fourth-, fifth- and higher-order linearized governing equations from the lower-order equations without the requirement of formulating the problem from the first principle. Three examples including the van der Pol damped nonlinear oscillator are presented to illustrate the excellent agreement with approximate solution using the exact frequency. [Copyright &y& Elsevier]

The Gupta-type many-body potential was applied to describe the interactions between atoms in zinc nanoclusters. From the calculated ground state structures, obtained by Brownian-type molecular dynamic simulation, we investigated the temperature effect of zinc clusters. We studied in particular the constant volume specific heat CV which is a thermodynamic quantity and also the relative bond length Lindemann parameter d which is a geometric quantity. Effort is devoted to revealing the anomalies observed in these quantities for Zn clusters and making a comparison with those of the typical sp-type metallic clusters. To this end, we have chosen to calculate the CV and d of clusters Znn for 29, 33, and 53 which are judged to be less stable by the energy difference and the second energy difference as well as 6, 36, 42, and 49 which are judged by the same energy criteria to be relatively more stable. Our results of simulation show that the structures of CV and d exhibit unusual phase transition behaviors which are drastically different from those of the usual metallic clusters. General scenarios observed in the simulation are the prevalence of the pre-melting phenomenon predicted in all of the clusters studied here. [ABSTRACT FROM AUTHOR]

The present study reported the efficacy of antisense oligonucleotides specific for N-methyl-d-aspartate receptor one (NR1) in reduction of motor symptom in a rat parkinsonian model, the unilateral 6-hydroxydopamine-lesioned rat. Significant reductions in apomorphine-induced contralateral rotation were only seen in the NR1 antisense-treated lesioned rats (after a single intraparenchymal dose of antisense to the lesioned neostriatum; 15 nmol in 3 μl of saline) at 1 or 2 days after the treatment. No motor effect was seen in the lesioned animals with control treatments (sham, treatment using NR1 sense oligonucleotides, randomized oligonucleotides or saline, respectively). In contrast, significant increases in expression of NR1 mRNA in the lesioned neostriatum were seen in rats with control treatments but not in rats with NR1 antisense treatment. Importantly, in the lesioned neostriatum that was treated with NR1 antisense, a significant reduction in NR1 protein expression was found and NR1 immunoreactivity was seen to reduce in perikarya of presumed striatal medium spiny neurons. The present data indicate that a single dose of NR1 antisense ameliorates motor symptom in the rat model. The efficacy of NR1 antisense is likely to be mediated by a selective knockdown in expression of NR1 mRNA and proteins in the presumed medium spiny neurons. [Copyright &y& Elsevier]

In the present study, we attempted to address the modulation of the gene expression of N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) glutamate receptors in the neostriatum of the 6-hydroxydopamine (6-OHDA)-lesioned rat, an animal model of Parkinson’s disease. After 2 weeks of lesion, reverse transcriptase-polymerase chain reactions (RT-PCRs) revealed significant reduction in GluR1 mRNA expression but a significant enhancement of NR1 mRNA expression in the striatal tissues of the lesioned side. No modulation in the mRNA expression of GluR2, GluR3, GluR4 and NR2B were found. Immunofluorescence with digital imaging analysis also demonstrated a significant reduction in GluR1 immunoreactivity in the lesioned neostriatum. Interestingly, the reduction in GluR1 immunoreactivity was primarily observed in presumed striatal medium spiny neurons but not in parvalbumin-labeled striatal GABAergic interneurons. Immunoreactivity for GluR2, GluR2/3, GluR4, NR1 and NR2B was unchanged in neurons of the neostriatum of the lesioned side. The present results indicate that there is an opposite trend in modulation in the gene expressions of GluR1 and NR1 in the neostriatum of 6-OHDA-lesioned rats after dopamine denervation. Modulation of GluR1 mRNA and immunoreactivity is likely to be limited in the striatal projection neurons. These findings have implications for the use of NMDA and AMPA receptor antagonists in the treatment of Parkinson’s disease. [Copyright &y& Elsevier]

This work presents an accurate in-plane vibration analysis of functionally graded material (FGM) skew plates with elastically restrained boundaries using the variational differential quadrature method (VDQM). The weak form of the governing equations is derived by integrating two-dimensional elasticity theory with Hamilton's principle. The differential and integral operators are directly converted into matrix forms, thereby removing the necessity for higher-order derivative approximations in the displacement field. Transformation matrices are then developed for both interior and boundary nodes to link the governing equations with the boundary conditions, leading to the formulation of the vibration eigenvalue equations for FGM skew plates. Various factors, including aspect ratios, skew angles, boundary restraints, and gradient indices, are considered to investigate the in-plane vibration mode characteristics of FGM skew plates. Detailed solution procedures are provided, and numerical examples using the proposed solutions indicate that the VDQM exhibits superior numerical convergence and stability compared to other existing methods. The study also investigates the influence of highly skewed plates (75°), where stress singularities arise at the corners. This aspect is crucial for in-plane vibration analysis and has garnered limited attention in the existing literature. Furthermore, the dynamic analysis of FGM skew plates reveals a coupling between normal and tangential vibration modes. [ABSTRACT FROM AUTHOR]

Explores the effects of planning on complex decisionmaking processes, through a partial computer simulation exploring the effects of planning on organizational decision processes based on a framework of the garbage can model of organizational choice. What the garbage-can model entails; How this model views the decisionmaking process of a decentralized organization; Effects of planning on the garbage-can model.

• The nonlinear vibrations are obtained for the polyer plates with and without GPLs. • Uniform and functionally graded distribution forms of graphene platelets are considered. • Differential governing equations of motion are derived. • Natural frequencies of first four vibration modes are examined. • Research results demonstrate the nonlinear vibration behaviors. The comparative researches of the nonlinear vibrations are obtained among the pure polymer plate and three types of graphene platelet reinforced polymer composite plates under combined the transverse and parametric excitations. All edges of the pure polymer and graphene platelet reinforced polymer composite plates are simply supported. Both the uniform and functionally graded distribution forms of the graphene platelets are considered. The differential governing equations of motion for the pure polymer and graphene platelet reinforced polymer composite plates are derived based on the first-order shear deformation plate theory, von Kármán strain displacement relationship and Hamilton principle. The fourth-order Galerkin truncation is employed to discretize the partial differential governing equations of motion to four-degree-of-freedom nonlinear dynamical system. The natural frequencies of the first four vibration modes are examined for the pure polymer and graphene platelet reinforced polymer composite plates with different geometric characteristics. In order to compare the nonlinear vibrations of the prestressed pure polymer and prestressed graphene platelet reinforced polymer composite plates subjected to the transverse point excitation and in-plane uniaxial/biaxial excitations, the time histories, phase portraits and Poincare maps are presented. Some validated results are conducted to present the accuracy of the present approach. The effects of the distribution forms and weight fractions of the graphene platelets on the nonlinear vibrations for the graphene platelet reinforced polymer composite plates are investigated in detail. The research results demonstrate that the nonlinear vibration behaviors of the prestressed pure polymer plate under the complex excitations can be remarkably stabilized by the reinforcement of the graphene platelets. [ABSTRACT FROM AUTHOR]

This study explores a modified active noise control (ANC) system using a Bayesian inference approach as a pre-processing method. The key aspect of low-frequency noise attenuation is investigated with the existing control algorithms, the conventional filtered-x least mean square (FxLMS) algorithm and a new convex structure via an FxLMS/F algorithm (C-FxLMS/F), that combine Bayesian inference with a dynamic linear model (DLM). The combination of a Bayesian approach and a DLM comprises the statistic strategy and a descriptive time series, which is conductive to raw signal pre-processing and concurrently generating a predicted signal as a reference signal. For signal processing, pretreatment enables the determination of the noise characteristics of the operating machine and its feedback to the control system. This is an important input to enable the time domain control algorithm to prevent environmental disturbance and time-delay effects. In addition, the use of active control theory mainly relies on the response time of secondary source generation. The predicted signals based on prior observational information and Bayesian inference afford an alternative to the normal costs of the secondary path, such as those associated with electro-acoustic signal conversion and computation efforts in the control algorithm. In this work, the combination of a Bayesian approach and an FxLMS algorithm is studied via a case study. To explore more applicability, the combination of a C-FxLMS/F algorithm with Bayesian inference is also investigated, and a convergence analysis is presented. The in-situ measurement data obtained from a construction site acoustic apparatus is used for analysis. The simulation results are presented via two illustrative cases. In addition, a comparison for three different signal forms under the effect of Bayesian inference is also discussed. It is found that a Bayesian inference approach based on DLM is workable in the ANC system, and the convergence performance is superior to that of an ANC system without Bayesian inference. This suggests that to implement such a system for signal control, it is better to enhance the final system performance in the time-domain field of ANC algorithms. This pre-processing system based on a characteristic strategy and having a low computational loss is needed not only to reduce the time-delay compromise, but also to prevent the sudden disturbance of the reference signal. [ABSTRACT FROM AUTHOR]

This work presents a novel computational approach, the DSC regularized Dirac-delta method, for the vibration analysis of functionally graded graphene-platelet reinforced (FG-GPLR) porous beams resting on a Winkler–Pasternak elastic foundation under a moving load. Based on the Timoshenko beam theory, the energy functional of the beam model is represented by a newly constructed basis function and is minimized under the variational principle. To account for the properties of composite materials, the Halpin–Tsai model is used to predict the elastic modulus of graphene-reinforced composites. A coupling of the DSC regularized Dirac-delta method and the Newmark– β integration scheme is then adopted for solving the dynamic problem. The DSC-based approach exhibits controllable accuracy for approximations and shows excellent flexibility in handling time-dependent moving load problems, because the equally spaced grid system used in the DSC numerical approach can achieve a preferable representation of moving load sources. An intensive parametric study is provided with a particular focus on the influence of moving loads, foundation supports and material properties (e.g., weight fraction, porosity distribution, dispersion pattern and geometry size of graphene reinforcements). First-known solutions reported in tabular and graphical forms should be useful for researchers and engineers in designing such beam problems. [ABSTRACT FROM AUTHOR]

A theoretical model for the generation of thermo-acoustic waves from a heated point source in a free-space and a half-space is proposed, where the source is suspended over a substrate. By directly applying the analytical results of a point source to a thin line thermo-acoustic speaker, the acoustic pressure field generated by the periodically heated thin line can be derived using a mathematical integration technique. To further generalize the results from a thin line speaker to a thin line array, the acoustic pressure response generated by the line array speaker can also be implemented in both free- and half-spaces. In this work, the characteristics of pressure fields generated by the thin line array are investigated in detail. The established model is well validated by comparing with the existing experimental results. The present findings not only can be extended to investigate thermo-acoustic responses generated by arbitrary sources, and also it can provide important design guidelines for the manipulation and optimization of thin line array thermo-acoustic devices. [ABSTRACT FROM AUTHOR]

Abstract: We consider the -dimensional generalized Liénard system driven by the scalar p-Laplacian, is an symmetric matrix of constants. Using the degree theory, we establish some criteria to guarantee the existence of periodic solutions for the above system, which generalize and improve on the corresponding results in the related literature. [Copyright &y& Elsevier]

• A magnetic levitation-based hybrid energy harvester is proposed. • A tri-stable mechanism is incorporated to enhance the working efficiency. • The system works well under low-frequency excitation levels (3–8 Hz and 0.3–1 g). • Portable electronics can be driven by the present harvester under low frequencies. A magnetic levitation-based hybrid energy harvester is proposed in this work. The new harvester consists of a tri-stable nonlinearity-enhanced mechanism that not only enhances the energy transfer through resonant inter-well oscillations, and also offers a wider bandwidth under low-frequency excitation levels. This integrated unit that combines a slider-driven electromagnetic generator (EMG) and a sliding-mode triboelectric nanogenerator (TENG) can harness more energy from vibration motions, thus resulting in a higher power density. In this study, both theoretical modelling and experimental studies are presented to investigate the dynamic characterization of the mechanical design, in which only four outer magnets are deployed on a plane to establish a triple-well nonlinear behaviour. Magnetic forces of this harvester are calculated by the magnetizing current method and the formation of tri-stable potential wells in the dynamic system is verified by a bifurcation analysis. In addition, a prototype of the harvester is fabricated and tested by an electrodynamic shaker system. The results show that the prototype exhibits a frequency bandwidth of 3–8 Hz and generates an output power of 6.9 mW and 6.44 mW in both horizontal and vertical orientations at a frequency of 8 Hz and 1 g acceleration, respectively. A performance study is also conducted to show that the proposed technique can produce sufficient power output as compared to other electromagnetic-triboelectric devices. [ABSTRACT FROM AUTHOR]

With the aid of an efficient meshless numerical solution and the reproducing kernel particle method, the feasibility for investigating the nonlinear vibrations of the carbon fiber reinforced composite rectangular plate with the random material properties is studied in this paper. A geometrically nonlinear mathematical model is established based on the classical plate theory. According to the derived governing equation of motion by using the principle of virtual displacement, the nonlinear vibration behaviors of the carbon fiber reinforced composite plates with various edge supports are investigated. The linear and nonlinear eigenvalues and corresponding eigenvectors are calculated iteratively by using the dimensionless amplitude. The stochastic meshless method is proved to have a good computational accuracy for the composite plate, and exhibits an optimal choice for the shape function and constraint of the essential boundary conditions. The useful conclusions are obtained regarding the effect of the material and geometrical parameters including the boundary condition, length-width ratio, plate length and carbon fiber content on the nonlinear responses in the framework of the meshless method. [ABSTRACT FROM AUTHOR]

We introduce a new optimization algorithm that combines the basin-hopping method, which can be used to efficiently map out an energy landscape associated with minima, with the multicanonical Monte Carlo method, which encourages the system to move out of energy traps during the computation. As an example of implementing the algorithm for the global minimization of a multivariable system, we consider the Lennard-Jones systems containing 150–185 particles, and find that the new algorithm is more efficient than the original basin-hopping method. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Circulating antibodies that specifically bind polyethylene glycol (PEG), a polymer routinely used in protein and nanoparticle therapeutics, have been associated with reduced efficacy and increased adverse reactions to some PEGylated therapeutics. In addition to acute induction of anti-PEG antibodies (APA) by PEGylated drugs, typically low but detectable levels of APA are also found in up to 70% of the general population. Despite the broad implications of APA, the dynamics of APA-mediated clearance of PEGylated drugs, and why many patients continue to respond to PEGylated drugs despite the presence of pre-existing APA, remains not well understood. Here, we developed a minimal physiologically based pharmacokinetic (mPBPK) model that incorporates various properties of APA and PEGylated drugs. Our mPBPK model reproduced clinical PK data of APA-mediated accelerated blood clearance of pegloticase, as well as APA-dependent elimination of PEGyated liposomes in mice. Our model predicts that the prolonged circulation of PEGylated drugs will be compromised only at APA concentrations greater than ~500 ng/mL, providing a quantitative explanation to why the effects of APA on PEGylated treatments appear to be limited in most patients. This mPBPK model is readily adaptable to other PEGylated drugs and particles to predict the precise levels of APA that could render them ineffective, providing a powerful tool to support the development and interpretation of preclinical and clinical studies of various PEGylated therapeutics. [ABSTRACT FROM AUTHOR]

• This paper investigates vibrations of graphene nanoplatelet reinforced microplate. • GNPL reinforced microplate is resting on Winkler elastic foundation. • Nonlinear partial differential governing equations of motion are obtained. • Partial differential equations are reduced to nonlinear algebraic eigenvalue equations. • Efficiency and accuracy of present approach are verified. This paper investigates the small-scale effect on the linear and nonlinear vibrations of the graphene nanoplatelet (GNPL) reinforced functionally gradient piezoelectric composite microplate based on the nonlocal constitutive relation and von Karman geometric nonlinearity. The GNPL reinforced functionally gradient piezoelectric composite microplate is resting on the Winkler elastic foundation and is subjected to an external electric potential. The parallel model of Halpin Tsai is used to compute the effective Young's modulus of the GNPL reinforced functionally gradient piezoelectric composite microplate. The Poisson's ratio, mass density and piezoelectric properties of the GNPL reinforced functionally gradient piezoelectric composite microplate are calculated by using the rule of mixture. Hamilton's principle is adopted to obtain the higher-order nonlinear partial differential governing equations of motion for the GNPL reinforced functionally gradient piezoelectric composite microplate. The partial differential governing equations of motion are reduced to a system of the nonlinear algebraic eigenvalue equations by using the differential quadrature (DQ) method and are solved by an iteration progress. The efficiency and accuracy of the present approach are verified by comparing with the existed results. Both uniformly and functionally distributing graphene nanoplatelets (GNPLs) are considered to investigate the effects of the GNPL concentration, external voltage, nonlocal parameter, geometrical and piezoelectric characteristics of the GNPLs as well as the elasticity coefficient of the Winkler elastic foundation on the linear and nonlinear dynamic behaviors of the GNPL reinforced functionally gradient piezoelectric composite microplate with various boundary conditions. The numerical results clearly manifest that the GNPLs can significantly enhance the structural stiffness of the micro-electro-mechanical system (MEMS). [ABSTRACT FROM AUTHOR]