Abstract

Artificial immune system is a class of computational intelligence methods drawing inspiration from biological immune system. As one type of popular artificial immune computing model, clonal selection algorithm (CSA) has been widely used for many optimization problems. When dealing with complex optimization problems, such as the characteristics of multimodal, high-dimension, rotational, the traditional CSA often suffers from diversity loss, poor search ability, premature convergence and stagnation. To address the problems, a modified combinatorial recombination is introduced to bring diversity to the population and avoid the premature convergence. Moreover, the success-history based adaptive mutation strategy is introduced to form a success-history based adaptive mutation based clonal selection algorithm to improve the search ability. The mutation operator is also modified and analyzed through experimental comparison. To further improve the precision and cope with the stagnation, the gene knockout strategy is proposed. The proposed algorithm is tested on CEC 2014 benchmarks and compared with state-of-the-art evolutionary algorithms. The experimental results show that MSHCSA is quite competitive.

Abstract

Segregation behaviors of Cu at α-Al (1 1 1) (1 1 1)/ δ^′-Al₃Li (1 1 1) interface were investigated with the first-principle pseudopotential plane-wave method. The results show that the most stable atomic coordination relations for α-Al (1 1 1)/δ^′-Al₃Li (1 1 1) interface is the structure of which the ABC stacking order of FCC lattice along (1 1 1) direction is kept at both two interfaces of Al and Al₃Li phases. At 1/4 ML coverage, Cu atom is inclined to be segregated at α-Al (1 1 1)/δ^′-Al₃Li (1 1 1) interface by adopting the interstitial rather than the substitution mode. The favorite interstitial site is the position where Cu atom is surrounded by three symmetrical Al atoms. Based on the calculation of separation work, we predicted that interstitial Cu can effectively improve the strength of the whole interface region, especially the area inside Al matrix, this is in agreement with the experimental results.

Abstract

The sandstone from the Oligocene Xiaganchaigou Formation (E₃) in the Lengdong area, Qaidam Basin, China, is extensively distributed and acts as an effective regional reservoir for hydrocarbon accumulation. Based on thin sections, scanning electron microscopy (SEM), X-ray diffraction (XRD) image analysis and cathodoluminescence (CL), a comprehensive analysis of the sedimentology, petrography, diagenesis and reservoir quality of the Oligocene sandstone reservoirs of the Xiaganchaigou (E₃) Formation in the Lengdong area, Qaidam Basin, are studied. The sandstones in the Lengdong area are classified as argillaceous sandstone, silty sandstone, fine sandstone, medium sandstone, pebbly sandstone, conglomeratic sandstone and conglomerate based on their grain sizes, degrees of sorting, and matrix contents. Five sedimentary facies were identified in the Xiaganchaigou Formation (E₃) of the Lengdong area, Qaidam Basin: distributary channel, interdistributary bay, mouth bar, central bar and distal sand sheet facies. Their major diagenetic processes include compaction, carbonate cementation and feldspar and calcite cement dissolution. The porosity and permeability values of the fine sandstone, conglomerate, and conglomeratic sandstone are the highest, followed by those of the medium sandstone and silty sandstone, and the argillaceous sandstone and pebbly sandstone have the lowest porosity and permeability values. The diagenetic sequence in the study area ranges from the eodiagenesis B stage to the mesodiagenetic A stage. Compaction has significantly reduced the primary porosity. Carbonate cements, mainly calcite cements, occlude pores by precipitating in intergranular and intragranular spaces. Dissolution largely contributes to increasing the secondary porosity. The well-sorted and relatively coarser-grained sandstones that formed in higher-energy sedimentary facies (distributary channel, mouth bar and central bar) have a better reservoir quality than the poorly sorted, clay-rich sandstones that formed in low-energy environments (interdistributary bay and distal sand sheet). Based on the comprehensive analysis of petrographic data, diagenesis and sedimentary facies, the reservoir in the Lengdong area is classified into three types: type A, type B and type C. Type A, located in the center of the study area, is the most favorable reservoir, while type C sandstone is the last to consider when looking for a good reservoir. This study can guide hydrocarbon exploration in the Lengdong area, as well as in northwestern China and similar areas throughout the world.

Abstract

This paper studies the optimization and implementation of human-machine dialog system based on cloud computing technology. Firstly, the coarse-perceived hash generation based on the formant frequency is studied, and the detail-aware hash generation based on the energy difference in the time domain is studied. Then, the combination of coarse-perceived hash and detail-aware hash is elaborated. Secondly, the algorithm is tested and emulated. The algorithm matches the coarse-perceived hash sequence with fewer bits, and returns the voice number with similar rough features to the index voice after matching successfully, and matches the detail-aware hash sequence of the corresponding number voice. Then, the exact match of the result is gotten. Finally, it is concluded that the algorithm in this paper can effectively recognize the human voice.

Abstract

In LDA model, independence assumptions in the Dirichlet distribution of the topic proportions lead to the inability to model the connections between topics. Some researchers have attempted to break them and thus obtained more powerful topic models. Following this strategy, by using an association matrix to measure the association between latent topics, we develop an associated topic model (ATM), in which consecutive sentences are considered important and the topic assignments for words are jointly determined by the association matrix and the sentence level topic distributions, instead of the document-specific topic distributions only. This approach gives a more realistic modeling of latent topic connections where the presence of a topic may be connected with the presence of another. We derive a collapsed Gibbs sampling algorithm for inference and parameter estimation for the ATM. The experimental results demonstrate that the ATM gives a more practical interpretation and is capable of learning more associated topics.

Abstract

Abstract

Abstract

Drilling of carbon fiber reinforced polymer (CFRP) is a challenging task in modern manufacturing sector and machining induced delamination is one of the major problems affecting assembly precision. In this work, a new three-dimensional (3D) finite element model is developed to study the chip formation and entrance delamination in drilling of CFRP composites on the microscopic level. Fiber phase, matrix phase and equivalent homogeneous phase in the multi-phase model have different constitutive behaviors, respectively. A comparative drilling test, in which the cement carbide drill and unidirectional CFRP laminate are employed, is conducted to validate the proposedmodel in terms of the delamination and the similar changing trend is obtained. Microscopic mechanism of entrance delamination together with the chip formation process at four special fiber cutting angles (0°, 45°, 90° and 135°) is investigated. Moreover, the peeling force is also predicted. The results show that the delamination occurrence and the chip formation are both strongly dependent on the fiber cutting angle. The length of entrance delamination rises with increasing fiber cutting angles. Negligible delamination at 0° is attributed to the compression by the minor flank face. For 45° and 90°, the delamination resulted from the mode III fracture. At 135°, serious delamination which is driven by the mode I and III fractures is more inclined to occur and the peeling force reaches its maximum. Such numerical models can help understand the mechanism of hole entrance delamination further and provide guidance for the damage-free drilling of CFRP.

Abstract

The spring-in deviation results in the extra stresses around the joints of the composite C-beam and metallic parts when they are assembled together. These extra stresses affect the composite elevator’s fatigue life, which should be explored with the fatigue experimentation. The paper presents the experimental investigation on the effect of spring-in deviation on the fatigue life of the composite elevator assembly. The investigation seeks to build the relationship between the spring-in and the fatigue life in order to determine the spring-in threshold during the course of assembling. The phenomenological model of the composite C-beam is constructed to predict the stresses around the joints. Based on the predicted spring-in induced stresses around the joints, pre-stresses are precisely added to the fatigue specimen when conducting the fatigue experiment. At last, the relationship curve of the spring-in on the composite C-beam’s fatigue life is obtained from the experimental data. Giving the fatigue life accepting limits, the maximum accepting spring-in deviation during the course of assembling could be obtained from the relationship curve. The reported work will enhance the understanding of assembling the composites with spring-in deviation in the civil aircraft industry.

Abstract

Reduction of a low-grade nickel laterite ore with carbon monoxide to produce Fe-Ni alloy was investigated using a thermo-gravimetric analysis (TGA) method. Non-isothermal reduction tests with a fixed heating rate of 10 °C/min from room temperature to 1200 °C were carried out to determine the different reduction stages and reaction products in each state. Combining measured mass losses with theoretically calculated values together with X-ray diffraction analysis, the products of different reduction stages were identified and a reaction path was established. Isothermal reduction tests with temperatures ranging from 500 °C to 1100 °C were performed to evaluate the temperature dependence of the reduction kinetics. Various kinetic models were fitted to the experimental data to further determine the rate-controlling step in the isothermal tests. Then, two groups of TG experiments were carried out to study the effect of CO flow rate and sample mass on the rate of reaction. The results indicated that the reduction rate increases with the increase of the reduction temperature from 500 °C to 1100 °C. More alloy products are formed and the apparent activation energies increase from 8.6 to 14.7 kJ/mol with the increase of the reduction temperature from 700 °C to 1100 °C. Accordingly, it was proposed that diffusion of CO in the gas bulk and through the pores of the laterite ore sample bed are the rate limiting steps.

Abstract

Copper slag, a by-product of copper pyrometallurgy, inevitably contains a certain amount of copper. Oxygen-enriched smelting technologies increase the copper content in slag indirectly because of the production of higher-grade matte. The effect of iron phase evolution on the copper content in slag during the slag cleaning process in an electric furnace was investigated using the method of combining theory with experiments. Based on the analysis, the main factors that impede the separation of slag and copper/matte were determined. Subsequently, the properties of slag were analyzed after decreasing the magnetite content within the slag. The experimental results showed that decreases in magnetite content were beneficial for the separation of copper and slag because of the decrease of slag viscosity. Nevertheless, Cu-Fe alloys formed when magnetite was completely reduced to metallic iron, and the foaming slag was formed at 1250 °C. Furthermore, the distribution of copper in the reduced slags was studied in detail.

Abstract

To improve the success rate of locating hydrocarbon reservoirs in pre-Cenozoic inland compressional basins, taking the Early Yanshanian succession of eastern Yihezhuang salient as an example, this paper studied the sedimentary facies and sequence stratigraphic patterns. First, through seismic profiles, well logs, cores and outcrops, the sequence framework was established and internal sedimentary facies were identified. Further, according to analysis of single-wells and connecting-wells, the vertical evolution and horizontal distribution of sedimentation inside the sequence frameworks were discussed. The following results were acquired: (1) meandering river characterized by dual structures superposing each other was developed, and the dual structures can be further divided into three kinds; (2) the entire Early Yanshanian succession was interpreted as one first-order sequence, composed of three third-order sequences, including SQ-Fz1, SQ-Fz2 and SQ-St from bottom to top. Each third-order sequence can be further divided into three system tracts; (3) in different system tracts, different types of dual structures developed separately, and sedimentary bodies showed different horizontal distribution scales and vertical superposition patterns. Finally, the model of sequence stratigraphic patterns was established. This study enhanced the use of sequence stratigraphy to inland tectonically active basins, and would be helpful to predict reservoirs in pre-Cenozoic residual basins.

Abstract

\(\hbox {SrTiO}_{3}\) and Bi-doped \(\hbox {SrTiO}_{3}\) films were fabricated with different device structures using the sol–gel method for non-volatile memory applications, and their resistance-switching behaviour, endurance and retention characteristics were investigated. \(\hbox {SrTiO}_{3}\) and \(\hbox {Sr}_{0.92}\hbox {Bi}_{0.08}\hbox {TiO}_{3}\) films grown on Si or Pt have the same phase structure, morphologies and grain size; however, the grain size of the \(\hbox {Sr}_{0.92}\hbox {Bi}_{0.08}\hbox {TiO}_{3}\) films grown on Si is slightly larger than those of the \(\hbox {SrTiO}_{3}\) films grown on Si and the \(\hbox {Sr}_{0.92}\hbox {Bi}_{0.08}\hbox {TiO}_{3}\) films grown on Pt. The \(\hbox {SrTiO}_{3}\) or \(\hbox {Sr}_{0.92}\hbox {Bi}_{0.08}\hbox {TiO}_{3}\) films grown on Si or Pt all exhibit bipolar resistive-switching behaviour and follow the same conductive mechanism; however, the \(\hbox {Ag}/\hbox {Sr}_{0.92}\hbox {Bi}_{0.08}\hbox {TiO}_{3}/\hbox {Si}\) device possesses the highest \(R_{\mathrm{HRS}}{/}R_{\mathrm{LRS}}\) of \(10^{5}\) and the best endurance and retention characteristics. The doping of Bi is conducive to enhance the \(R_{\mathrm{HRS}}{/}R_{\mathrm{LRS}}\) of the \(\hbox {SrTiO}_{3}\) films; meanwhile, the Si substrates help improve the endurance and retention characteristics of the \(\hbox {Sr}_{0.92}\hbox {Bi}_{0.08}\hbox {TiO}_{3}\) films.

Abstract

Abstract

Greenhouse gas emissions from agricultural soils contribute substantially to global atmospheric composition. Nitrous oxide (N₂O) is one important greenhouse gas induces global warming. Nitrification inhibitors (NI) or biochar can be effective soil N₂O emission mitigation strategies for agricultural soils. However, due to differences in crop physiological traits or agricultural management, the effectiveness of mitigation strategies varies among agricultural systems. Camellia oleifera is a woody oil plant widely grown and requires intensive N input, which will potentially increase N₂O emissions. Thereby, mitigation of N₂O emissions from C. oleifera field soil is vital for sustainable C. oleifera development. Besides NI, incorporation of C. oleifera fruit shell-derived biochar into its soil will benefit waste management and simultaneous mitigation of N₂O emissions but this has not been investigated. Here, we conducted two studies to examine effects of biochar addition and NI (dicyandiamide, DCD) application on N₂O emissions from C. oleifera field soil with different N (urea or NH₄NO₃) and incubation temperatures. Biochar effects on nitrification rates varied among N treatments. Biochar applied in combination with DCD further reduced nitrification rates (for urea treatment, decreased from 1.1 to 0.3 mg kg⁻¹ day⁻¹). Biochar addition consistently increased soil N₂O emissions (for urea treatment, increased from 0.03 to 0.08 ng g⁻¹ h⁻¹) and their temperature sensitivity. DCD application reduced soil N₂O emissions with greater reductions with urea application. In future cultivation of intensively managed C. oleifera gardens, NI should be applied to mitigate N₂O emissions if biochar is added, especially when urea is used.

Abstract

Short texts have become the prevalent format of information on the Internet. Inferring the topics of this type of messages becomes a critical and challenging task for many applications. Due to the length of short texts, conventional topic models (e.g., latent Dirichlet allocation and its variants) suffer from the severe data sparsity problem which makes topic modeling of short texts difficult and unreliable. Recently, word embeddings have been proved effective to capture semantic and syntactic information about words, which can be used to induce similarity measures and semantic correlations among words. Enlightened by this, in this paper, we design a novel model for short text topic modeling, referred as Conditional Random Field regularized Topic Model (CRFTM). CRFTM not only develops a generalized solution to alleviate the sparsity problem by aggregating short texts into pseudo-documents, but also leverages a Conditional Random Field regularized model that encourages semantically related words to share the same topic assignment. Experimental results on two real-world datasets show that our method can extract more coherent topics, and significantly outperform state-of-the-art baselines on several evaluation metrics.

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Abstract

Abstract

In this paper, the synchronous supply chain management information system for mass customization in e-commerce is studied. The principle of chain management and the mechanism of mass customization in e-commerce are discussed. It is pointed out that chain management aims at chain value. Secondly, the paper explains the mechanism of chain management, and points out that chain management improves the value of chain by establishing modular operation units, identifying and managing bottlenecks, identifying and eliminating waste under the action of collaborative planning and control. This paper discusses chain management from the strategic point of view, and draws a conclusion that the mass customization operation management system based on chain management has the characteristics of sustainable competitive advantage. Finally, the process description system of implementing chain management is given, and the dynamic collaborative scheduling optimization of MC e-commerce in supply chain environment is also given. The practical case analysis shows that the method designed in this paper has a good practical effect.

Abstract

In this work, with the flexible carbon fiber (CF) fabric and polyphenylene sulfide (PPS) nonwovens as reinforcement and matrix, respectively, the composites were prepared by thermo-compression lamination to obtain the rigid CF/PPS composite laminates. We investigated effects of the pretreating on CF fabric with silane coupling agent (KH560) and the thermal treatment on the mechanical properties, crystalline behaviors and micromorphologies of the composites. It was found that the appropriate thermal treatment conditions and the use of KH560 are necessary to strengthen the interface bonding between CF and PPS matrix, which is verified by the morphologies of fracture surfaces of CF/PPS composites. Under the thermal treatment condition of 240 °C for 1 h, the CF/PPS composite laminate has a relatively high crystallinity and mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus, interlaminar shear strength and impact strength of the composite laminates reach 930.4 MPa, 9.4 GPa, 950.6 MPa, 60.5 GPa, 40.3 MPa and 68.7 MPa.