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This paper presents a mathematical model in the biofilm phase and in the gas phase that has been successfully applied to investigate various aspects of the biofiltration process. The mixtures of volatile organic compounds (VOCs) are emitted from a wide range of industries, such as chemical, petrochemical, pharmaceutical, pulp paper mills, printing and paint workshops, etc. The objective of the present study is, presence of high n-propanol loading negatively affected the toluene removal; however, n-propanol removal was not affected by the presence of toluene and was effectively removed in the biofilter despite high toluene loadings. A model for toluene and n-propanol biofiltration could predict the cross-inhibition effect of n-propanol on toluene removal. Further, we studied the effects of many physical and biological parameters on model prediction. The mathematical equations (2.12)-(2.16) which are non-linear partial differential equations are solved by using the homotopy perturbation technique. Also, we derived the semi-analytical results for toluene and n -propanol concentrations for saturated and unsaturated kinetics. It is verified that the proposed solution is validated by comparing it with numerical solutions. • Here mathematical modelling is developed for bio-filtration in the biofilm phase. • The adopted model investigate various aspects of the bio-filtration process. • Analytical results is obtained via Homotopy Perturbation Technique. • The obtained solutions is verified for accuracy with existing literature. [ABSTRACT FROM AUTHOR]

In this paper, a new fourth-order compact finite difference scheme is proposed to solve the extended Fisher-Kolmogorov (EFK) equation. The scheme is three-level and implicit nonlinear. A new time discretization technique is adopted in the new scheme. The priori estimate and convergence of the numerical solution are obtained by using the discrete energy method, and the optimal error estimation in the maximum norm shows that the proposed numerical scheme has second-order accuracy in time and fourth-order accuracy in space. Finally, the theoretical analysis is supported by the numerical results of several examples. [ABSTRACT FROM AUTHOR]

• New FWM design to compensate for the uncertainty caused by continuous and disruptive time delays. • Adapting the FWM method to the LMI in the form of an optimization problem. • Combined modeling of energy storage system with RES in large-scale power system. • Using state observer with FWM for better observability of closed-loop system poles in the design process. Due to the high penetration of renewable energy sources (RES) such as wind units in power systems, the need to check the stability of transmission networks has been given more attention than before. Therefore, in this paper, due to the importance of the topic, the wide area damping controller (WADC) has been used for the battery energy storage system (BESS) connected to the photovoltaic unit and the permanent magnet synchronous generator (PMSG) in the dc link. The WADC design is based on free weight matrices (FWM), which can solve a set of constraints based on the linear matrix inequality (LMI) based on the delay-dependent feedback control theory. The working method is that the constraints related to LMI are considered in such a way that it has the ability to tolerate the maximum amount of time delay. FWM has been used to communicate between LMI constraints and the maximum value of the time delay margin. FWM matrices are also based on an iterative algorithm based on linearization of the conical complement, which tries to search for the most optimal value for the control parameters. To implement the simulation results in MATLAB software, an improved power system of 16 machines has been used, the results of which are clearly analyzed and show the superiority of the proposed method compared to other mentioned methods. [ABSTRACT FROM AUTHOR]

The application of regression machine learning techniques is crucial for the analysis and optimization of energy systems based on geothermal energy to produce freshwater, power, and heating. This study applied regression machine learning techniques to investigate and optimize a geothermal tri-generation energy system that combines double-flash geothermal energy, humidification-dehumidification desalination, and transcritical carbon dioxide Rankine cycle. The goal was to produce freshwater, power, and heating. The algorithms performed remarkably well, with R-squared values surpassing 96 %. It is worth mentioning that for specific parameters like freshwater production, heating capacity, and efficiency, the R-squared values exceeded an impressive 99 %. The optimum conditions include maintaining a Rankine pressure ratio of 3, a mass flow rate of 30 kg/s, a geothermal temperature of 220 °C, and a turbine pressure ratio of 2.2. By following these ideal parameters, it is possible to achieve the highest level of system performance. This will lead to the production of 7.88 kg/s of freshwater, the generation of 1283 kW of power, a heating capacity of 30.8 kg/s, and an impressive system efficiency of 24.98 %. The findings reveal that the integration of regression machine learning algorithms in geothermal energy systems for freshwater, power, and heating production holds great promise for a sustainable and efficient future. • Regression machine learning techniques were applied on a geothermal-based system. • The goal was to produce freshwater, power, and heating. • The algorithms performed remarkably well, with R-squared values surpassing 96 %. • 7.9 kg/s of freshwater, 1283 kW of power, and 30.8 kg/s of heating were achieved. • Optimized integrated system efficiency was 24.98 %. [ABSTRACT FROM AUTHOR]

Thermal and flow features of nanofluid are explored under the impact of an external magnetic field whereas fluid is flowing inside a vertical square duct. It is assumed that the sunlight tends to heat up the duct. Two fins are attached to the duct that receive sunlight of uniform intensity. Two walls of the duct contain a fixed temperature and, are exposed to the direct sunlight under the assumption of a particular thermal boundary condition and developed flow. The governing equations of the problem are solved by the finite volume method. The taller fins not only act as significant obstacles causing reduction in flow velocity and frictional losses but also contribute to enhanced the rate of heat transfer more extensively with the surfaces of fins. Higher Rayleigh number fosters buoyancy-driven natural convection, causing a change in the thermal signature and diminution in thermal distribution over the domain. The magnetic force also tends to impede thermal diffusion, thus hampering heat transfer within the flow. The pressure gradient and the nanoparticle volume fraction significantly reduce fRe. On the other hand, the fin height, Rayleigh number and the magnetic parameter cause an enhancement in the Nusselt number and fRe. Finally, introducing a modern perspective into the research approach, machine learning technique (Neural Fitting app) was incorporated to refine the analysis. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present a thorough investigation into the impact of an external magnetic field on the flow and thermal properties of nanofluid within a vertically oriented square duct exposed to sunlight-induced heating. The duct incorporates two rectangular fins attached to one set of adjacent walls, receiving uniform sunlight intensity. In contrast, the other two walls feature a thin lubricant film which causes the fluid slip rather than adhesion. Assuming hydrodynamically and thermally developed laminar flow, the study employs a specific thermal boundary condition, enforcing a constant heat flux per unit axial length and a uniform peripheral temperature at the sun-exposed duct walls. Considering the balance between computational efficiency and solution accuracy, the finite volume method is employed to solve the governing partial differential equations. It has been observed that the magnetic parameter induces magnetic damping, resulting in a reduction in velocity distribution and qualitative alterations in flow patterns within the duct due to the heightened impact of the applied magnetic field. The presence of taller fins acts as significant obstacles which divert the flow and cause additional frictional losses, resulting in an overall reduction in flow speed. Elevated Rayleigh numbers amplify natural convection currents, producing a more pronounced change in velocity distribution while qualitatively transforming the thermal signature within the duct. Further, the slip parameter increases the overall velocity distribution while exerting a minimal impact on the thermal distribution, due to a reduction in resistance along the walls with lubrication, facilitating smoother fluid motion and leading to a more widespread velocity profile throughout the duct. Finally, to bring a contemporary perspective to the research methodology, modern techniques such as machine learning were integrated. The widely adopted Neural Fitting app was employed to enhance the precision of the analysis. [ABSTRACT FROM AUTHOR]

• Eyring fluid flow across two deformable rotating disks is considered. • The fluid flow is affected by thermophoretic particle deposition and double diffusion. • Impacts of Hall current and ion slip are also assumed. • The model is supported by multiple slips at the boundary of the surface. • The problem is solved numerically. This work emphasizes the characteristics of thermophoretic particle deposition on Ree-Eyring fluid flow with Hall current and Ion slip effects between two deformable spinning disks. The novelty of the envisioned model is strengthened by considering generalized Fourier and Fick laws with thermal source/sink. The proposed model is optimized by taking multiple slip boundary constraints at the surface. The equations that govern the flow are simplified with the use of the proper transformations. The numerical solution is obtained using the boundary value problem of fourth order (bvp4c) method. Graphical representations of the emerging parameters are presented. Numerical values of skin friction coefficient, local Nusselt, and Stanton number are highlighted in tabular form. The velocity field depicts a deteriorating behavior on incrementing the Reynold number. For augmented values of Hall and ion slip parameters fluid velocity elevates. An upsurge is noticed in the axial and radial velocities on amplifying the rotation parameter. On augmenting the thermophoretic parameter the particle deposition at the interface of the upper disk diminishes. Growing values of rotation parameter, Weissenberg, and Reynold numbers imply an additional resistance to the fluid flow that ultimately reinforced the surface drag force causing a decline in the fluid velocity. The rate of heat transmission accelerates on enhancing the Reynold number, however, heat flux exhibits a decay on augmenting the thermal slip parameter. On augmenting the thermophoretic parameter particle deposition deteriorates at the interface of the upper disk. An excellent concordance is noticed when the outcomes are contrasted with the previous literature. For the value of the rotation parameter β = - 1 and β = - 8 the percentage error of the present analysis with Imtiaz et al. [68] are 0.00001 and 0.00002. [ABSTRACT FROM AUTHOR]

• Metal oxides with high RI will improve the sensing performance of fiber sensors. • Compared to silver-based sensors, the maximum sensitivity of TiO 2 composite film sensors has increased by 16.92 %. • Compared to silver-based sensors, the maximum sensitivity of ZnO composite film sensors has increased by 4.62 %. • The maximum temperature sensitivity of the two composite membrane sensors is 4.9 nm/℃ and 4.3 nm/℃, respectively. With the widespread application of fiber surface plasmon resonance (SPR) sensors in the field of biochemical sensing, especially in the detection of large molecules such as proteins, the sensitivity of traditional fiber SPR sensors has made it difficult to meet the requirements of detection accuracy in practical applications. This article proposes and proves an effective method for selecting the optimal metal oxide material to improve the sensing performance of SPR sensors. Metal oxides (TiO 2 and ZnO) can improve the sensitivity by enhancing the evanescent field of fiber SPR phenomenon. Through simulation, it was found that when the metal oxide film of the composite film sensor maintains the same thickness, the metal oxide with a high effective refractive index (RI) has a better improvement effect on the sensitivity of the SPR sensor. Experimental results show that the maximum RI sensitivity of TiO 2 composite film sensors and ZnO composite film sensors in the RI range of 1.333–1.420 is 15,200 nm/RIU and 13,600 nm/RIU, respectively. Compared to silver-based sensors, RI sensitivity has increased by 16.92 % and 4.62 %, respectively. To further verify the enhancement effect of different metal oxides on fiber sensors, another layer of PDMS film is deposited on TiO 2 and ZnO films. Within the temperature sensing range, the maximum temperature sensitivity of these two composite film temperature sensors is 4.9 nm/°C and 4.3 nm/°C, respectively. Overall, metal oxides with high RI can improve the sensing performance of fiber optic sensors. [ABSTRACT FROM AUTHOR]

We consider the problem of scheduling jobs with sizes, release times and delivery times on identical parallel batch machines. All machines have the same capacity. Each machine can simultaneously process several jobs as a batch as long as the total size of these jobs does not exceed the capacity. The release time, processing time and delivery time of a batch are defined to be the latest release time, longest processing time and largest delivery time of all the jobs in the batch, respectively. The objective is to minimize the maximum delivery completion time, i.e., the time by which all jobs are delivered. For this strongly NP-hard problem, there does not exist any polynomial time algorithm with approximation ratio better than 2 unless P=NP, even if all jobs have equal processing times and all release times and delivery times are zero. We present an algorithm with approximation ratio arbitrarily close to 2. • Study parallel batch scheduling of minimizing maximum delivery completion time. • Jobs have non-identical sizes, release times and delivery times. • Present an algorithm with approximation ratio arbitrarily close to 2. [ABSTRACT FROM AUTHOR]

Currently, bionic drag reduction is a popular research topic, particularly the drag reduction effect of a grooved structure. To investigate entropy generation caused by the effect of a grooved structure on flow, this study used Fluent software and large eddy simulation (LES) technology to analyze entropy generation in flow over a plate with a grooved structure. The purpose of this work is to provide a theoretical basis for reducing drag on such a structure. The study showed that a grooved structure was able to reduce entropy generation in the flow process. At 30 m/s, the total entropy generation in the near-wall region decreased by approximately 25%, and at 40 m/s, it decreased by approximately 19%. However, the grooved structure did not have a sustained effect on the subsequent flow. Moreover, as the distance from the wall in the normal direction increased, the effect gradually decreased. The secondary vortex that formed within the grooved structure changed the velocity gradient in the normal direction in the near-wall region and weakened the shearing action between flow layers, thereby reducing the entropy generation caused by viscous dissipation. Moreover, the reduction in entropy generation in the near-wall region was significant, decreasing by 49% and 58% at y+=5 when the flow rate was 30 and 40 m/s, respectively. Since the grooved structure was unable to inhibit the velocity fluctuations in turbulent flow, the magnitude of the entropy generation caused by the turbulence did not decrease. However, the distribution of the entropy generation caused by turbulent dissipation was more uniform in the region with the grooved structure than in the region with the smooth structure. The entropy generation at the tip of the grooved structure was one order of magnitude larger than the entropy generation at the near-wall region in the flow field. Even though the entropy generation caused by turbulent dissipation was predominant in that region, the entropy generation caused by viscous dissipation should not be ignored. [ABSTRACT FROM AUTHOR]

[Display omitted] • Here Darcy-Forchheimer relation is accounted in flow of viscous fluid. • Soret and Dufour effects are considered. • Chemical reaction is addressed in concentration equation for the mass transfer analysis. • Numerical results are obtained via Shooting method. The main purpose of this work is to analyze chemically reactive Darcy-Forchheimer nanoliquid flow towards a stretched surface. Buongiorno's model is utilized for the nanoliquid importance. Additionally, Soret and Dufour characteristics are also considered. Gyrotactic microorganisms with chemically reactive flow are considered. The given partial differential systems are converted into dimensionless ordinary expressions with the implementation of suitable transformation. Non-dimensional systems are solved through Newton built in-shooting technique. Graphical outcomes for temperature, microorganisms' field, velocity and concentration versus secondary variable are discussed. Numerical outcomes of drag force, density number and heat transport rate for sundry parameters are examined. A reduction occurs in velocity for higher porosity variable. Higher estimation of Dufour number upsurges the temperature. Similar impact for temperature is seen for random motion and thermophoresis variables. Concentration upsurges for higher Soret number, while reverse effect holds for Schmidt number. An increment in heat transport rate occurs for higher Dufour number. Microorganisms' fluid diminishes for higher Peclet number, while reverse impact seen for density number. [ABSTRACT FROM AUTHOR]

An ultra-high sensitivity temperature sensor based on photonic crystal fiber (PCF) is proposed and demonstrated. The central hole and the two holes coated with nanoscale gold film are assumed to be filled with temperature sensitive liquid. The refractive index of the liquid decreases as the temperature increases with the temperature sensitive coefficient of -3.9 × 10 −4 / o C. The liquid of the central hole with high refractive index supports liquid-core mode. As the phase matching condition is satisfied, the liquid-core mode couples to the surface plasmon polariton mode and presents energy loss. The influences of the PCF structural parameters and the thickness of the gold film on the resonance wavelength, loss value and sensitivity are studied. The resonance wavelength and confinement loss increase as the temperature increases. The average sensitivity can reach to 9.89 nm/ o C ( ∼ 25359 nm/RIU) as the temperature changes from 35 °C to 45 °C and the R-square is 0.99992. By replacing the liquid core by silica core, we find the sensitivity is very low. We also compare the PCF without liquid in the holes coated with gold film by our structure and find that the sensitivity is nearly unchanged and the confinement loss is slightly decreased. [ABSTRACT FROM AUTHOR]

A novel ultra-wide bandwidth photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance (SPR) is proposed. The PCF has two large cladding air holes in the direction of y-axis that are selectively coated with gold films to create resonance. There are two small holes in the direction of x-axis, which provides high birefringence. The polarization characteristics of PCF are studied by finite element method (FEM). The numerical simulation results indicate that the loss of y-polarized core mode is 718.87 dB/cm, while the loss of x-polarized core mode is only 0.95 dB/cm at the resonant wavelength of 1.55 µm. The extinction ratio is better than 20 dB at the wavelength ranging from 1.43 to 1.79 µm, the corresponding bandwidth is 360 nm. [ABSTRACT FROM AUTHOR]

In this paper, the asymptotic homogenization method is applied to the filtration theory of a generalized Newtonian fluid in periodic porous media. The asymptotic expansion of non-Newtonian viscosity is obtained by the asymptotic expansion of the second invariant of the strain tensor. The so-called local problem in periodic cells is presented to describe the microscale transport of a generalized Newtonian fluid in porous media. Based on nonlinear tensor function theory, the filtration law of generalized Newtonian fluid is obtained, which is used to describe the average process of filtration. A new numerical method to solve the local problem is proposed by using the least squares finite element method, and the permeability coefficient and effective viscosity of a generalized Newtonian fluid in porous media are evaluated. The exact solution of Poiseuille's flow in the microtube for a power-law fluid is obtained by theoretical analysis to verify the accuracy of the proposed model. Finally, the local transports of a shear-thinning Modified Cross fluid in two classical 2D porous structures are simulated and the dependencies of the permeability tensor and effective viscosity on the pressure gradient in porous structures are analyzed, which validates the proposed models and numerical methods. • A local problem on periodic cells is presented for the flow of a generalized Newtonian fluid in a single pore. • Developed the least squares finite element method to solve local problems. • The filtration law of a generalized Newtonian fluid is proposed using nonlinear tensor function theory. • Exact solutions for Poiseuille's flow of a power-law fluid in microtubes are obtained. • Local problems are solved and the permeability and effective viscosity in 2D porous structures are obtained. [ABSTRACT FROM AUTHOR]

A compact glucose sensor is proposed by using a short length of photonic crystal fiber inserted in a Sagnac loop interferometer. Spectrum shift in response to the RI of glucose solution with a high average sensitivity of 22 130 nm/RIU is achieved, equivalent to 0.76 mg/dL of glucose in water, which is lower than 70 mg/dL for efficient detection of hypoglycemia episodes. And the simplicity of the fiber structure makes the sensor production very cost effective. We aimed to provide a potential effective method for glucose detection in patients with hypoglycemia. [ABSTRACT FROM AUTHOR]

A novel photonic crystal fiber polarization filter with Au-coated and liquid-filled air holes is designed in this paper. The coupling theory is introduced to explain the complete coupling and incomplete coupling. We can adjust the resonance point to the communication band by optimizing the parameters of the fiber structure. Numerical simulation results demonstrate that the resonance strength can reach 434 dB cm −1 at the communication wavelength of 1.31 μm in x-polarized direction. By filling liquid analyte can help adjust the resonance peak to the proper place. Furthermore, when the fiber length of L equals to 0.1 cm, the crosstalk peak value can reach 353.74 dB at the wavelength of 1.31 μm, and the bandwidth of the crosstalk better than 20 dB can reach 80 nm when the length of the fiber L is 400 μm. These characteristics make it a promising candidate for designing new types of polarization filter devices. [ABSTRACT FROM AUTHOR]

We design a crystal photonic fiber (PCF) polarization filter with asymmetric structure and two large air-holes coated with gold film. The influence of the thickness of metal layers and the diameter of large air-holes on the filtering characteristic is investigated using finite element method (FEM). In calculations, the sixth and the third order surface plasma modes (SPM) are presented. The resonance positions are well separated by the asymmetry of the structure in vertical direction. The loss of unwanted polarization is 829 and 1267 times than that of wanted polarization at 1.48 and 1.55 μm respectively. When the fiber length is 3 mm, the crosstalk is 1055 dB and 927 dB for 1.48 and 1.55 μm. The bandwidth with crosstalk better than 20 dB can reach to 1000 nm, covering almost all communication band. What’s more, gold excitation of SPR and silver excitation of SPR are compared and studied. [ABSTRACT FROM AUTHOR]

In recent years, photonic crystal fibers have played an important role in the field of optical communications, and the addition of metal materials to photonic crystal fibers have offered new ways to improve the transmission characteristics of optical fibers. We design a new type of gold-coated photonic crystal filter, which utilizes the surface plasmon resonance effect, and study it by using the finite element method. In this paper, we optimise the structure parameters and analyze the numerical results. The numerical results show that the thickness of metal layer and the air holes near the fiber core strongly affect the performance of the polarization filter. For the operating wavelength of 1550 nm, the loss in the y-polarization direction can be as high as 906.9 dB/cm, which is much larger than the x-polarization direction. When the fiber length is longer than 100 μm, the crosstalk in the wavelength range from 1.4 μm to 1.9 μm is greater than 20 dB. The proposed optical fiber can find application as an optical fiber polarization filter. [ABSTRACT FROM AUTHOR]

A kind of multi channel dual-core photonic crystal fiber polarization beam splitter is designed. We analyze the effects of the lattice parameters and the thickness of gold layer on the beam splitting by the finite element method. Numerical results show that the thickness of metal layer and the size of the air holes near the fiber cores are closely linked with the nature of the polarization beam splitter. We also obtain that extinction ratio can reach −73.87 dB at 1 . 55 μ m wavelength and at 1 . 41 μ m, 1 . 65 μ m extinction ratio can reach 30.8978 dB and 31.1741 dB, respectively. The comparison of the effect on the characteristic of the photonic crystal fiber with coating no gold is also taken into account. [ABSTRACT FROM AUTHOR]

In cross-ply laminates, the shape of delamination areas, which form due to low velocity impact, have two subtle features, which have been observed consistently in numerous experiments. Those are the pointed delamination tips and the intact zone between the lobes of delamination. However, there have not been any account available in the literature how they can be consistently captured through numerical modelling, and hence these features in published modelling results were often absent. It is the objective of this paper to identify the underlying modelling considerations so that these features can be captured with confidence. A key and unique reason has been identified in each case. Namely, inclusion of intra-laminar damage allows to reproduce the pointed delamination tips, while the gap between the lobes of delamination can be captured by models with sufficiently refined mesh, where friction between the laminas is taken into account. The capability of capturing these subtle features helps to raise the level of fidelity on the simulation of delamination due to impact. [ABSTRACT FROM AUTHOR]

We study the problem of scheduling n jobs on m parallel batching machines with nested processing set restrictions. Each job has a release time before which it cannot be processed, and has a restricted set of batching machines to which it can be assigned, called its processing set. Two distinct processing sets are either nested or disjoint. Each batching machine can process up to B ( B < n ) jobs simultaneously as a batch, where B is known as the batch capacity. The processing time of a batch is the maximum of the processing times of the jobs belonging to it. The objective is to minimize the makespan (maximum completion time) of the schedule. When all jobs are released at the same time, we present a fast algorithm with approximation ratio 3 − 1 / m . For the case of unequal release times, we develop a fast algorithm with approximation ratio 4 − 1 / m , as well as a polynomial time approximation scheme (PTAS). [ABSTRACT FROM AUTHOR]

A polarization filter based on photonic crystal fiber selectively coated with gold film is investigated. The loss spectra and the dispersion characteristics of the designed polarization filter are studied and analyzed by the finite element method. Simulation results show that the loss of core mode is 433.65 dB/cm in y polarization and 2.64 dB/cm in x polarization at the wavelength of 1.55 µm, respectively. The bandwidth of extinction ratio greater than −20 dB is 150 nm. The corresponding wavelength range is from 1.48 µm to 1.63 µm. The position and size of the little air holes along with the thickness of gold film showed influence on the polarization filter properties. And the proposed polarization filter has stable properties of with difference size and position of the little air holes. The designed polarization filter showing excellent properties can be used in polarizations filter in communication transmission. [ABSTRACT FROM AUTHOR]

We propose a heterogeneous thirteen-core few-mode fiber, which has the excellent characteristics of low crosstalk (XT), large effective mode field area (A e f f) and low dispersion slope (D s l o p e). The double high refractive index ring can precisely control the effective refractive index difference between the LP mode in the core and reduce intra-core XT. The relative spatial efficiency (RSE) of the 13-core 6-mode fiber reaches 33.84, and the number of spatial channels is as high as 130. The inter-core crosstalk is less than −60 dB/km at 1550 nm. The results show that the proposed fiber with low crosstalk and large A e f f is sufficient to satisfy the requirements of long-distance transmission in the future. • A heterogeneous 13-core 6-mode fiber is proposed to reduce inter-core crosstalk while enhancing bending resistance. • Heterogeneous core arrangement can increase the propagation constant difference between adjacent cores. • The maximum differential mode delay for the highest order mode (LP 12) and LP 01 mode is 28 ps/m. • The number of spatial channels of 13-core 6-mode fiber based on space division multiplexing is as high as 130. [ABSTRACT FROM AUTHOR]

A new type of tellurite glass based on dual-core microstructured optical fiber with an Au wire has been numerically evaluated. This novel substance is a suitable optical fiber material for nonlinear applications due to its high nonlinear coefficient. A full-vector finite element method is employed to analyze the characteristics of the polarization splitter. A splitter with an ultrashort length of 1.079 mm and a high extinction ratio of 174.92 dB at the wavelength of 1.55 μ m has been obtained. Moreover, the splitter exhibits a bandwidth with an extinction ratio as high as 20 dB of about 70 nm. An effective mode area A eff of the optical fiber of 21.53 μ m 2 for one of the supermodes of the x even mode has been calculated. [ABSTRACT FROM AUTHOR]

A novel stress analysis method is developed for the efficient design of radially laminated annular beams/shafts subject to arbitrary load combinations. The analysis is conducted using classic laminate theory (CLT) in conjunction with a mechanics of materials (MoM) approach based on the plane section assumption. Global loads are related to the global deformations and are expressed in terms of the generalised laminate strains in CLT. The analysis is verified against MoM for a homogeneous and isotropic tube. Further validation against the finite element method is shown for general cases in terms of loading and laminate layups with almost perfect agreement. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a fourth-order compact and energy conservative difference scheme for three-dimensional Rosenau-RLW equation is proposed. The scheme is a two-level and nonlinear-implicit scheme. It is proved by the discrete energy method that the compact scheme is solvable, the convergence and stability of the difference scheme is obtained, and its numerical convergence order is O ( τ 2 + h 4 ) in the L ∞ -norm. We discuss an iterative algorithm for solving the nonlinear algebraical system generated by the nonlinear compact scheme and prove its convergence. Numerical experiment results show that the theory is accurate and the method is efficient and reliable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quantitative surface and Hirshfeld surface analysis of nicorandil molecules were studied. • Solubility data was analyzed by using extended Hildebrand solubility approach. • Preferential solvation were investigated via inverse Kirkwood–Buff integrals method. • Dissolution properties and enthalpy–entropy compensation were studied. The quantum-chemical quantities of highest negative surface electrostatic potential and lowest surface average local ionization energy as well as Hirshfeld surface were used herein to explain the electrostatic features of both basicity and acidity of nicorandil molecule. The primary electrophilic and nucleophilic sites are the -N and > NH groups, respectively. According to the nicorandil solubility in solutions of isopropanol (1) + water (2), ethanol (1) + water (2), DMF (1) + water (2), and methanol (1) + water (2), preferential solvation of nicorandil was investigated using the famous inverse Kirkwood-Buff integrals approach. In poor water composition areas, nicorandil was surrounded preferentially by organic solvent, showing the selective solvation of nicorandil by methanol/DMF/ethanol/isopropanol. This performance was due to high basicity of organic solvents compared with water, which favors interactions with nicorandil's acidic groups. The Hansen solubility parameter was used to evaluate the performance of nicorandil solubility in depth. The derived dissolution Gibbs energy change, enthalpy and entropy indicated that the solubilization capacity improved with increasing methanol/DMF/ethanol/isopropanol compositions. As the proportions of methanol/DMF/ethanol/isopropanol rose, analysis of enthalpy–entropy compensation revealed a shift in main dissolving mechanism from enthalpy-driven to entropy-driven (alcohol solutions) or from entropy-driven to enthalpy-driven (DMF solutions). [ABSTRACT FROM AUTHOR]

A short-length polarization beam splitter is designed. It is based on a simple structure dual-core photonic crystal fiber (DC-PCF), and possesses short-length. We research the effects of DC-PCF structure parameters on performances of the splitter by finite element method (FEM). The results show that the extinction ratio of the 249 μ m - long splitter can reach −50.7 dB at the communication wavelength of 1.55 μ m . Furthermore, the extinction ratio of the 506 μ m - long splitter can reach −61.6 dB at the communication wavelength of 1.31 μ m . The bandwidths of extinction ratio better than −20 dB are about 17 nm and 12 nm at wavelength of 1.55 μ m and 1.31 μ m , respectively. [ABSTRACT FROM AUTHOR]

Network motifs are local structural patterns and elementary functional units of complex networks in real world, which can have significant impacts on the global behavior of these systems. Many models are able to reproduce complex networks mimicking a series of global features of real systems, however the local features such as motifs in real networks have not been well represented. We propose a model to grow scale-free networks with tunable motif distributions through a combined operation of preferential attachment and triad motif seeding steps. Numerical experiments show that the constructed networks have adjustable distributions of the local triad motifs, meanwhile preserving the global features of power-law distributions of node degree, short average path lengths of nodes, and highly clustered structures. [ABSTRACT FROM AUTHOR]

This paper results from a reflection on the problem of finite rotations in plates and shells and its presentation in finite element formulation, a well-attended subject with a wide diversity of treatments, often extremely complicated. For instance, the very topic attracted 3 out of total 15 chapters over 120 out of total 494 pages in a monograph on nonlinear FEA [5] . In another instance, a 71 page journal paper was published [2] specifically on this topic alone. Review papers on this matter can be found in various sources including Appl Mech Rev, (e.g. Ibrahimbegovic, 1997 [8] ). No attempt is to be made on reviewing these sophisticated approaches but the present paper will bring answers to questions, if they have ever been asked, such as whether the sophistication in existing approaches is really necessary and whether there is a much simpler and conceptually more direct and accurate approach. A proper re-examination of the existing approaches would reveal a fundamental inconsistency: rigid body rotations have been assumed without reservation to describe the deformations of deformable plates and shells. After re-establishing the consistency based on the very basics of conventional plate and shell theories as a simple reflection, one can conclude surprisingly that the whole issue on ‘finite rotations’ results from a logic fallacy of faulty generalisation. The so-called ‘rotations’ should be displacement gradients instead. They can be considered as ‘rotations’ as conventionally perceived hitherto under the condition of small deformation. Somehow, the concept of ‘rotations’ got generalised regardless the magnitude of the deformation. Instead of calling the problem as ‘finite displacement gradients’ as it should be called, a falsely generalised term of ‘finite rotations’ have been used. Since they were called ‘rotations’, the definition of those of rigid body kinematics has been taken for granted. Finite displacement gradients should not present any additional problem apart from introducing nonlinear nature into the problem, which can be addressed as a geometrically nonlinear problem in a conventional manner. However, along the line of a falsely generalised concept of finite rigid body rotations, complications have been the norm. The complicated accounts on the ‘finite rotation’ problem in the literature, which might have enhanced the understanding of rigid body kinematics, are entirely unnecessary as far as the deformable plates and shells are concerned, involving infinitesimal or finite deformations. [ABSTRACT FROM AUTHOR]

The effects of different polar solvents on the performance of solvent vapor annealing treated polymer solar cell (PSC) with a structure of ITO/ZnO/PTB7: PC 71 BM/MoO 3 /Ag was systematically investigated by applying different polar solvents, including methanol, ethanol, dimethylsulfoxide, acetone and isopropanol. By analyzing the variation of PSC performance and the morphology of active layer, we found that both the solubility parameters ( Δ ) and viscosity of solvent were playing an important role in controlling the morphology of PTB7: PC 71 BM blend. Especially, the PSC treated by methanol with high Δ and low viscosity exhibited a remarkable enhancement of power conversion efficiency from 6.55% to 8.13%. The performance improvement was mainly due to the formation of the nanoscale crystallization of PTB7: PC 71 BM blend and the moderated aggregation of PC 71 BM, resulting in efficient charge separation, balanced charge transport and suppressed charge recombination. [ABSTRACT FROM AUTHOR]

Most of the hydraulic concrete structures in cold regions of China are suffering freezing–thawing (FT) deterioration and the first step to choose repairing measures is to appropriately and quantitatively evaluate the FT damage degree in concrete. The current evaluating parameters for FT damage in concrete, such as resonant frequency and ultrasonic wave velocity are all phenomenological descriptions and cannot reveal the essence of the FT damage, which is the initiation and propagation of microcracks. This paper proposes a method to evaluate FT-damage in concrete based on vacuum–epoxy-impregnation method and digital-image-processing (DIP) technique. Quantitative microcrack analysis and mechanical tests including compressive tests, flexural tests and axial tensile tests were performed for the concrete specimens with/without air-entrainment suffered different FT cycles. Evolutions of microcrack characteristics of the matrix cracks (including Interfacial Transition Zone (ITZ) cracks and mortar cracks) in the concrete specimens were thoroughly investigated. Relationships between the relative mechanical properties and the microcrack density were established. Results show that the length density, area density and crack width of microcracks in the matrix of concrete all increase with the increase of damage degree and the ITZ cracks instead of the mortar cracks are the major part of FT-caused microcracks. The high correlation coefficients between the mechanical properties and microcrack density indicate that quantitative microcrack analysis could be used as a powerful and promising tool of quantifying FT damage in concrete. [ABSTRACT FROM AUTHOR]

NaTaO 3 nanoparticles were synthesized by hydrothermal method and then the corresponding visible-light photocatalyst (Er 3+ :YAlO 3 /Pt–NaTaO 3 ) was successfully prepared by mixing with Er 3+ :YAlO 3 as up-conversion luminescence agent and supporting Pt as co-catalyst. The prepared Er 3+ :YAlO 3 /Pt–NaTaO 3 was characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). By studying some influence factors such as Er 3+ :YAlO 3 and Pt–NaTaO 3 mass ratio, heat-treated temperature, visible-light irradiation time and solution acidity (pH) on the visible-light photocatalytic hydrogen production caused by Er 3+ :YAlO 3 /Pt–NaTaO 3 , it was found that the prepared Er 3+ :YAlO 3 /Pt–NaTaO 3 with 0.3:1.0 mass ratio heat-treated at 500 °C for 120 min in weak acidic solution (pH = 5.0–6.0) with 5.0 wt% methanol displayed a high photocatalytic activity in hydrogen production from water solution. [ABSTRACT FROM AUTHOR]

A series of Yb, B and Ga doped Er 3+ :Y 3 Al 5 O 12 (Er:YAG) as up-conversion luminescence agents were synthesized using sol–gel method. After that, their corresponding TiO 2 coated composites (Er 3+ :Y 3 Al 5 O 12 /TiO 2 (Er:YAG/TiO 2 ), Yb-doped Er 3+ :Y 3 Al 5 O 12 /TiO 2 (YbEr:YAG/TiO 2 ), Yb and B-doped Er 3+ :Y 3 Al 5 O 12 /TiO 2 (YbEr:(B)YAG/TiO 2 ), Yb and Ga doped Er 3+ :Y 3 Al 5 O 12 /TiO 2 (YbEr:(Ga)YAG/TiO 2 ) and Yb, B and Ga doped Er 3+ :Y 3 Al 5 O 12 /TiO 2 (YbEr:(B,Ga)YAG/TiO 2 )) as sonocatalysts were prepared by sol–gel coating process. The up-conversion luminescence agents and their coated composites were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). And that, the sonocatalytic activities were detected through the degradation of some organic dyes as model pollutants by UV–vis spectroscopy under ultrasonic irradiation. The influencing factors such as heat-treated temperature and heat-treated time on the sonocatalytic activity of YbEr:(B,Ga)YAG/TiO 2 coated composite were studied. In addition, the effects of ultrasonic irradiation time and initial dye concentration on the sonocatalytic degradation were also reviewed. The experimental results showed that the doping of Yb, B and Ga into Er:YAG/TiO 2 significantly enhanced its up-conversion luminescence capability, therefore, improved the sonocatalytic activity of Er:YAG/TiO 2 coated composite in the degradation of organic dyes. Particularly, YbEr:(B,Ga)YAG/TiO 2 coated composites with 3:7 mass ratio heat-treated at 550 °C for 60 min displayed the highest sonocatalytic activity. At last, the experiments indicated that the YbEr:(B,Ga)YAG/TiO 2 coated composite has also a good sonocatalytic activity to degrade other organic dyes under ultrasonic irradiation. [ABSTRACT FROM AUTHOR]

Continuous Fibre composite 3D printing (CF-3DP) technology is a newly developed Additive Manufacturing (AM) process. By employing continuous fibre as a reinforcement for the composite, the mechanical properties of the 3D printed part can be significantly improved. However, owing to the process's early stage of development, the mechanical performance of the printed material is still unable to compete with composites produced using conventional manufacturing processes. This can manly be attributed to lower fibre volume fractions and/or higher void content. The grand objective of the research project is to establish a demonstrator of practical applications, and in this paper, preparatory developments were carried out to pave the ground for the subsequent developments, including feedstock materials development, printing process development, and materials properties evaluation. Efforts has been made to increase fibre volume fracture, to reduce voids contents, to evaluate effective properties systematically. The static mechanical test results showed relatively good longitudinal tensile properties while matrix sensitive properties were low, as to be expected in UD composites with a relatively weak matrix material. The advantage of CF-3DP is to achieve fibre steering, and the steered fibre design can be achieved by the current process to realize novel composite structures in future study. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • High bandwidth scalar optical atomic magnetometer by direct repetition measurement. • Easily-built multipass cell helps sensitivity reach subpicotesla in kilohertz range. • Continuous and burst sampling mode to adapt performance capability of system. • Capable of working in earth's magnetic field without active or passive shielding. • Low atomic density at low temperature for more options of antirelaxation coatings. High-frequency ultraweak magnetic field measurements are essential. We demonstrate a scalar rubidium atomic magnetometer with effective measurement bandwidth of kilohertz and sensitivity of subpicotesla operating at a temperature of 365 K in an ambient field of 50 μT. The Faraday rotation signal is enhanced by a more simplified optical multipass cell compared to previous works. We developed an approach of continuous or burst sampling mode to maximize the frequency capability of the system, and propose a scheme of precise control pulse series as well as an analytical method of data processing. Experimental results show that high contrast atomic spin projection noise and free induction decay signal are observed, and a sampling rate of 2 kHz along with the sensitivity of 0.7 pT/Hz1/2 between 20 and 1000 Hz have been achieved. It would help further research in physics and biomedical investigations that need high bandwidth magnetometers or sensor arrays in the earth's field. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a theoretical investigation on an analyte-filled core self-calibration microstructured optical fiber plasmonic refractive index sensor. The proposed microstructured optical fiber sensor introduces the concept of simultaneous detection in different ranges of wavelength because the sensing performance of the sensor in different wavelength ranges is relatively high, which will be useful for high accuracy measurement. The resonant peak 1 and peak 2 are stronger and more sensitive to the variation of analyte refractive index than any other peaks in this kind of microstructured optical fiber. An average refractive index sensitivity of −4354.3nm/RIU (refractive index unit) and 2280nm/RIU in the dynamic index range from 1.46 to 1.485 as well as −2660nm/RIU and −4240nm/RIU from 1.50 to 1.52 corresponding to the peak 1 and peak 2 can be obtained, respectively. The self-calibration sensor demonstrates high linearity and accuracy. The influence of the structural parameters on the plasmonic excitations is also studied, with a view of turning and optimizing the resonant spectrum. [Copyright &y& Elsevier]

Abstract: In this paper, a high effective up-conversion luminescence agent (Er3+:Y3Al5O12) is synthesized by sol–gel method, and then its corresponding visible-light photocatalyst (Er3+:Y3Al5O12/Pt–TiO2) is successfully prepared by direct mixing and calcination methods. For comparison, Er3+:Y3Al5O12, Pt–TiO2 and Er3+:Y3Al5O12/Pt–TiO2 are all characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). At first, the up-conversion luminescence properties of Er3+:Y3Al5O12 are reviewed by excitation spectrum in visible-light region and emission spectrum in ultraviolet-light region. And then, under visible-light irradiation the visible-light photocatalytic activity of Er3+:Y3Al5O12/Pt–TiO2 is examined through photocatalytic hydrogen production from aqueous methanol solution. Lastly, the influence factors such as Er3+:Y3Al5O12 and Pt–TiO2 mole ratio, heat-treated temperature and heat-treated time on the visible-light photocatalytic hydrogen production activity of Er3+:Y3Al5O12/Pt–TiO2 are studied. Particularly, Er3+:Y3Al5O12/Pt–TiO2 with 6:100 M ratio heat-treated at 550 °C for 90 min shows the highest photocatalytic activity in hydrogen production from aqueous methanol solution. [Copyright &y& Elsevier]

Highlights: [•] Unit cell boundary conditions are derived for axial and circumferential periodicity. [•] This rigorous framework for unit cell modelling avoids pitfalls of intuitive methods. [•] The boundary conditions are validated for several circular and prismatic problems. [•] The boundary conditions are used in a model of a thermal barrier coating interface. [•] Models using the present boundary conditions agree closely with reference solutions. [Copyright &y& Elsevier]

In recent years, three-dimensional printing (3DP) technology has developed to include composite materials. Most of the development to date in this area has involved particulate or short fibre reinforced composites, whilst continuous fibre printing remains a relatively novel research area. This review paper focuses on the state-of-the-art of continuous fibre reinforced 3DP technology (CF-3DP). The materials and devices being used in the current studies are reviewed, and the different processing methods are discussed in detail. A thorough summary of the mechanical properties is provided. Despite improvements compared to 3D printed pure plastics, the performance of current continuous fibre 3D printed composites are not yet in a position to compete with conventionally processed composites due to defects and low fibre volume fraction. Finally, an overview of current potential applications are presented. However, challenges still remain in materials and process development. New design, modelling and analysis methods are needed before these novel composite structures can find their optimal applications. [ABSTRACT FROM AUTHOR]

Abstract: In order to characterize the recycled lower continental crust (LCC) in the Dabie orogen, 17 Early Cretaceous low-Mg adakitic (LMA) and 9 normal (non-adakitic) granitoids have been investigated for Srph name="sbnd" />Pb isotopes. Combined with literature data, LMA have low ƐNd(t) (−27.8 to −14.7) and 206Pb/204Pb(i) (15.69–17.16) and low to moderately high 87Sr/86Sr(i) (0.7066 to 0.7087) ratios. Normal granitoids yield isotope ratios similar to adakitic rocks, except a few with 87Sr/86Sr (i) up to 0.7105. Dabie LMA define a linear trend parallel to the North Hemisphere Reference Line (NHRL) in a 208Pb/204Pb(i)– 206Pb/204Pb(i) diagram. For a given 206Pb/204Pb(i), the 208Pb/204Pb(i) or ∆8/4 (152–217) of Dabie LMA are close to the majority of UHP gneisses and the Neoproterozoic mafic rocks from the northern margin of the South China Block (SCB), but significantly higher than adakitic rocks from the North China Block (∆8/4<150). Considering the commonly present Neoproterozoic inherited zircons, we suggest that the LMA in the Dabie orogen are derived from a thickened LCC that could be dominantly composed of ancient SCB lower crust. The Srph name="sbnd" />Pb isotopic composition of LMA are similar to those of Post-Collisional Mafic Igneous rocks (PCMI) from the Dabie orogen, but different to exhumed UHP rocks. The Srph name="sbnd" />Pb isotopic system of the mantle source of the PCMI could be enriched in components dominantly from delaminated LCC of the Dabie orogen instead of deeply subducted continental crust, which is in contrast to O- and C-isotope data by [Zhao, Z.F., Zheng, Y.F., Wei, C.S., Wu, Y.B., Chen, F.K., and Jahn, B.M., 2005. Zircon Ulement and C geochemistry of post-collisional mafic–ultramafic rocks from the Dabie orogen in east-central China. Lithos 83(1–2), 1–28; Dai, L.Q., Zhao, Z.F., Zheng, Y.F., Li, Q.L., Yang, Y.H., and Dai, M.N., 2011. Zircon Hf evidence for crust–mantle interaction during continental deep subduction. Earth and Planetary Science Letters 308, 229–244]. Combining the Srph name="sbnd" />Pbce:glyph name="sbnd" />C isotopic data, two types of commonly present magma components have been identified in the PCMI, reflecting crust–mantle interaction during the Triassic subduction and the Early Cretaceous orogen collapse, respectively. [Copyright &y& Elsevier]

Abstract: We present here a combined study of Early Cretaceous granodiorites, granites and mafic rocks from the Bengbu area on south-eastern margin of the North China Craton (NCC), in order to provide insights into the thinning mechanism of lithosphere on the cratonic margins. Zircon U–Pb and Ar–Ar dating reveals an adakitic–basaltic–granitic magma sequence with the adakitic intrusions (granodiorites; 123–115Ma) formed prior to the granites and mafic dykes (both ca.112Ma). The granodiorites are geochemically similar to low-Mg# adakitic rocks and isotopically have enriched Sr–Nd–Hf compositions, low radiogenic Pb (206Pb/204Pbi =16.524–17.017), and mantle-like δ18Ozircon (5.8±0.5‰). They were originated from the thickened lower continental crust (LCC) of the NCC. In contrast, the granites have low Sr/Y (<20), La/YbN, Dy/YbN, and prominent negative Eu anomalies, indicating their origination at the shallow middle-lower crustal levels. The mafic dykes are enriched in LREE relative to HREE, and exhibit negative anomalies of Nb, Ta, Ti and positive anomalies of Pb. They have low Nb/U, Ce/Pb, high La/Nb, Ba/Nb, enriched Sr–Nd isotopic compositions and low radiogenic Pb (206Pb/204Pbi =16.789 to 17.262), indicating LCC materials involved into the mantle sources. Modeling suggests derivation of the mafic dykes from the depleted upper mantle hybridized by 10–15% recycled LCC. The contrasting chemical characteristics of adakitic rocks and granites imply that recycling of the LCC was likely achieved through rapid foundering at 115–112Ma, which resulted in thinning of the overlying crust and hybridization of the underlying mantle with closely coeval generation of granitic and basaltic magmas. Anatexis of the pre-existing thickened LCC at 123–115Ma that attenuated the LCC itself and left the residues denser as a result of felsic (adakitic) melt extraction is proposed to have resulted in gravitational instability and foundering of the lithosphere. Such a temporal sequence of magma generation and processes of lithospheric thinning also occurred on north margin of the NCC and are quite similar to the mountain-root removal beneath the Dabie Orogen in central China. This manifests that previous melting of the LCC is perhaps an important trigger responsible for lithospheric foundering in orogenic belts and cartonic margins, where the lithosphere underwent pre-thickening by continental collisions and had stabilized over a long time. [Copyright &y& Elsevier]

Abstract: The geological implications of granitoid magmas with high Sr/Y and La/Yb are debated because these signatures can be produced by multiple processes. This study presents comprehensive major and trace element compositions and zircon SHRIMP U–Pb age data of 81 early Cretaceous granitoids and 4 mafic enclaves from the Dabie orogen to investigate partial melting of the thickened lower continental crust (LCC). On the basis of Sr/Y ratios, granitoids can be grouped into two magma series: (i) high Sr/Y granitoids (HSG) and (ii) normal granitoids with low Sr/Y. Relative to normal granitoids, HSG display the following distinct chemical features: (1) at given SiO2 and CaO contents, the HSG have significantly higher Sr than normal granitoids, defining two different trends in Sr versus SiO2, CaO diagrams; (2) highly depleted heavy rare earth element (REE) relative to middle and light REE with (Dy/Yb)N and (La/Yb)N up to 3.2 and 151, respectively; (3) variable and higher Nb/Ta; and (4) positive correlations among Sr/Y, (Dy/Yb)N, (La/Yb)N, and Nb/Ta. High Sr/Y, (La/Yb)N, (Dy/Yb)N, and Sr/CaO of HSG do not correlate with major elements (e.g., SiO2). Large variations in these ratios at a given SiO2 content indicate that these features do not reflect magma mixing or fractionation. HSG have higher Sr at a given CaO content and larger variation of (Dy/Yb)N than old crustal rocks (including exposed basement, global mafic LCC xenoliths, high Sr/Y TTG suites, and adakites in modern arcs). This precludes inheritance of the HSG chemical features from these source rocks. Instead, the chemical features of the HSG are best explained by partial melting of the thickened LCC with garnet-dominant, plagioclase-poor, and rutile-present residual lithologies. The coupled chemical features of the HSG are not observed in post-collisional granitoids younger than ca.130Ma, indicating removal of the eclogitic source and/or residuum of HSG underneath the orogen. These characteristic chemical relationships in the Dabie HSG may be applied to distinguish partial melts of thickened LCC from high Sr/Y intermediate-felsic magmatic rocks which do not show clear indications for melting depth. [Copyright &y& Elsevier]

Abstract: Adakites are commonly associated with porphyry Cu–Au ore deposits worldwide. Two groups of early Cretaceous adakites occur widely in central-eastern China but their association with mineralization contrasts sharply: adakites from the Lower Yangtze River Belt (LYRB) host one of the largest porphyry Cu–Au deposit belts in China, whereas those from the South Tan-Lu Fault (STLF), which is adjacent to the LYRB, are all ore-barren. These adakites, thus, provide a rare opportunity to explore the main factor that controls the genetic links between adakites and Cu–Au mineralization. Here we report new chronological, elemental and Sr–Nd–Pb isotopic data and present a comprehensive geochemical comparison for these two groups of adakites. At a given SiO2, the STLF adakites show lower Al2O3 and higher K2O, K2O/Na2O, MgO, Cr, Ni and Mg# than the LYRB adakites. These systematic differences may indicate a dry basaltic source for the STLF adakites and a water-enriched basaltic source for the LYRB adakites. The STLF adakites have high Sr/Y and (La/Yb)N, which are positively correlated, and low Sr/La and Ce/Pb, while the LYRB adakites show lower (La/Yb)N but higher Sr/Y, Sr/La and Ce/Pb than the STLF adakites. Furthermore, the LYRB adakites are characterized by highly radiogenic Pb isotopic compositions with 206Pb/204Pb(t) up to 18.8, which are clearly distinct from the STLF adakites with low radiogenic Pb (206Pb/204Pb(t)=15.8–16.4). Although the high Mg# of the two groups of adakites suggest reaction with mantle peridotites during magma ascent, the geochemical comparisons indicate that the STLF adakites were derived from partial melting of the delaminated eclogitic lower continental crust, while the LYRB adakites were derived from partial melting of the seawater-altered oceanic crust that was being subducted towards the LYRB during the early Cretaceous. The petrogenetic contrasts between these two groups of high-Mg adakites, therefore, indicate that the large-scale Cu–Au mineralization is associated with oceanic slab melting, not delamination or recycling of the ancient lower continental crust, as previously proposed. [Copyright &y& Elsevier]