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In this work, we introduce a class of black-box (BB) reductions called committed-programming reduction (CPRed) in the random oracle model (ROM) and obtain the following interesting results: (1) we demonstrate that some well-known schemes, including the full-domain hash (FDH) signature (Eurocrypt 1996) and the Boneh-Franklin identity-based encryption (IBE) scheme (Crypto 2001), are provably secure under CPReds; (2) we prove that a CPRed associated with an instance-extraction algorithm implies a reduction in the quantum ROM (QROM). This unifies several recent results, including the security of the Gentry-Peikert-Vaikuntanathan IBE scheme by Zhandry (Crypto 2012) and the key encapsulation mechanism (KEM) variants using the Fujisaki-Okamoto transform by Jiang et al. (Crypto 2018) in the QROM. Finally, we show that CPReds are incomparable to non-programming reductions (NPReds) and randomly-programming reductions (RPReds) formalized by Fischlin et al. (Asiacrypt 2010). [ABSTRACT FROM AUTHOR]

Based on the identity-based encryption (IBE) from lattices by Agrawal et al. (Eurocrypt’10), Micciancio and Peikert (Eurocrypt’12) presented a CCA1-secure public-key encryption (PKE), which has the best known efficiency in the standard model and can be used to obtain a CCA2-secure PKE from lattices by using the generic BCHK transform (SIAM J Comput, 2006) with a cost of introducing extra overheads to both computation and storage for the use of other primitives such as signatures and commitments. In this paper, we propose a more efficient standard model CCA2-secure PKE from lattices by carefully combining a different message encoding (which encodes the message into the most significant bits of the LWE’s “secret term”) with several nice algebraic properties of the tag-based lattice trapdoor and the LWE problem (such as unique witness and additive homomorphism). Compared to the best known lattice-based CCA1-secure PKE in the standard model due to Micciancio and Peikert (Eurocrypt’12), we not only directly achieve the CCA2-security without using any generic transform (and thus do not use signatures or commitments), but also reduce the noise parameter roughly by a factor of 3. This improvement makes our CCA2-secure PKE more efficient in terms of both computation and storage. In particular, when encrypting a 256-bit (respectively, 512-bit) message at 128-bit (respectively, 256-bit) security, the ciphertext size of our CCA2-secure PKE is even 33%–44% (respectively, 36%–46%) smaller than that of their CCA1-secure PKE. [ABSTRACT FROM AUTHOR]

In this paper, the self-infeed rolling process of thread shaft with medium carbon steel AISI 1045 is investigated. Firstly, the principle of the self-infeed rolling process is introduced and then the deformation mechanism is analyzed by finite element method. The numerical results show that deformation mainly occurs on the surface layer of blank, and the deformation degree is different in the tooth profile. The metal flows along both the axial direction and the radial direction. Next, the experimental studies of self-infeed rolling process are carried out. The numerical results are shown in good accordance with the experimental results. The grain at the top of tooth profile is refined, and the microstructures in the surface of tooth profile as well as bottom of tooth root are fibrous tissue which is dense and streamlined obviously. The hardness of the formed thread shaft is improved than that of the blank. [ABSTRACT FROM AUTHOR]

A number of spinning methods can be utilized to produce large sheaves such as crosshead sheaves. However, few studies have investigated the relationship and differences between these methods. Therefore, an exploration of spinning features is necessary. In this study, four typical spinning methods, including a novel counter-roller spinning method, were selected to study the forming process. Numerical simulation and experiment study were performed. A theoretical model was then proposed to determine the differences between each spinning method. Stress and strain distribution, thickness reduction, and spinning forces during the forming process were obtained, and results of the simulations and experiments matched well. Variations in the sheave thickness, stress value, and spinning force were observed with different spinning methods. Although all spinning methods investigated in this study could form sheaves, counter-roller spinning with a simple roller method demonstrated the smallest thickness reduction, spinning force, and forming stress. Therefore, the counter-roller spinning should be the first option for spinning large sheaves. [ABSTRACT FROM AUTHOR]

Mechanical clinching technology for joining aluminium alloy sheets has been a hot research topic in recent years. However, the clinched joint has a lower static strength than the welded joint and self-pierce riveted joint. In order to increase the strength of the clinched joint, a height-reducing method was investigated in the study. The material of the sheets is AL5052 which is widely used on the automotive body. Extensible dies were used to produce the clinched joint, while a flat die and a bumped die were used to produce the height-reduced joint. In the height-reducing process, the protrusion of the clinched joint was compressed by the flat die. The material of the protrusion flowed to the neck, which increased the strength of the joint by increasing the neck thickness. Different joints with different geometrical parameters were used to conduct the cross-tensile tests. The cross-tensile strength, energy absorption, failure mode and geometrical parameter of the joint are investigated. The results show that the cross-tensile strength and energy absorption of the joint can be increased by the height-reducing process. The main failure mode of the joints is neck fracture mode. The height-reducing method can increase the neck thickness with the decrease of the protrusion height. The height-reducing method was proved to be effective for increasing the strength of the clinched joint. [ABSTRACT FROM AUTHOR]

The high protrusion on the clinched joint affects the appearance of the joint. A height-reducing method was investigated in the work to reduce the protrusion height. The clinched joint was produced with AL5052 sheet and AL6061 sheet. Flat dies were used to conduct the height-reducing process in the experiment. A rivet was used in the height-reducing process to control the material flow of the protrusion and increase the strength of the joint. The cross-tensile strength, tension-shearing strength and energy absorption were investigated in the study. The cross-tensile strength and tension-shearing strength of the joint can be increased by the height-reducing method. The neck thickness also can be enlarged with the reduction of the protrusion. The height-reduced joint can absorb more energy than the clinched joint in the failure process. The height-reducing method was effective for reducing the protrusion height and increasing the strength of the joint produced with different sheets. [ABSTRACT FROM AUTHOR]

In order to solve the problems of die and tooling manufacturing and assembling for the foil forming, especially for the foil micro forming, high-pressure water jet forming (HPWJF), a new die-less forming process for foil parts is proposed. In the forming process, liquid medium such as water and oil is utilized as a flexible tool to deform the ultrathin foil. In this paper, the computational fluid dynamics (CFD) software Fluent was used to simulate the water jet generation in the water jet nozzle and high-speed water impacting on a rigid surface. And then, the effects of jetting distance on the jetting pressure were obtained. To measure the precise mechanical parameters of copper foils, a digital speckle test method was used to detect the tensile process. Local bulging experiment was conducted for the copper foil with a thickness of 50 μm. When the inlet pressure is 8.5 MPa, the suitable jetting distance is 40 mm for the 50-μm-thick copper foil. In such conditions, the bulging height of the copper foil is 1.20 mm in the experiment. The fluid-solid coupled method by using Fluent and Abaqus was applied to simulate the deformation of the copper foil. The errors between the simulated results and the experimental values are lower than 10 %. Furthermore, both the experiment and simulation for micro stretching of 30-μm-thick copper foil were performed. The cylinder die with a diameter of 3 mm and a height of 1.5 mm is used to form the copper foil. Results show that the copper foil cracks when the jetting distance is 24 mm, and the inlet pressure is 12 MPa. With the increase of the inlet pressure, the drawing depth of the copper foil gradually increases, and the bottom of the cylinder part thins gradually, and the wrinkling of the flange of the cylinder part becomes more and more severe. [ABSTRACT FROM AUTHOR]

Compared with the conventional single-roller spinning process, the double-roller clamping spinning(DRCS) process can effectively prevent the sheet metal surface wrinkling and improve the the production efficiency and the shape precision of final spun part. Based on ABAQUS/Explicit nonlinear finite element software, the finite element model of the multi-pass DRCS for the sheet metal is established, and the material model, the contact definition, the mesh generation, the loading trajectory and other key technical problems are solved. The simulations on the multi-pass DRCS of the ordinary Q235A steel cylindrical part with the arc-shaped surface flange are carried out. The effects of number of spinning passes on the production efficiency, the spinning moment, the shape error of the workpiece, and the wall thickness distribution of the final part are obtained. It is indicated definitely that with the increase of the number of spinning passes the geometrical precision of the spun part increases while the production efficiency reduces. Moreover, the variations of the spinning forces and the distributions of the stresses, strains, wall thickness during the multi-pass DRCS process are revealed. It is indicated that during the DRCS process the radical force is the largest, and the whole deformation area shows the tangential tensile strain and the radial compressive strain, while the thickness strain changes along the generatrix directions from the compressive strain on the outer edge of the flange to the tensile strain on the inner edge of the flange. Based on the G-CNC6135 NC lathe, the three-axis linkage computer-controlled experimental device for DRCS which is driven by the AC servo motor is developed. And then using the experimental device, the Q235A cylindrical parts with the arc-shape surface flange are formed by the DRCS. The simulation results of spun parts have good consistency with the experimental results, which verifies the feasibility of DRCS process and the reliability of the finite element model for DRCS. [ABSTRACT FROM AUTHOR]

Flubendiamide, which belongs to the new chemical class of phthalic acid diamides, is widely used against lepidopteron pests in a variety of vegetable and rice pests. It provides superior plant protection against a broad range of economically important lepidopterous pests, including Spodoptera exigua and Plutella xylostella. A determination method of flubendiamide in the cabbage was established in this paper. Flubendiamide in the cabbage was extracted with acetonitrile and ultrasonic extraction, and was purified by QuEChERS and analyzed by LC-MS/MS (liquid chromatography-tandem mass spectrometry). The results indicated that the average recovery of flubendiamide in the cabbage was 81.27 %-91.45 %, the coefficient of variation was 1.79 %-4.81 %, and the lowest detection concentration was 0.3 μg/kg. The extraction of flubendiamide from the cabbage and its analysis was in accordance with the pesticide residue criterion, i.e., simple, rapid, accurate, reproducible, stable, separatory, and convenient. It identifies and quantifies trace-level flubendiamide residues in the cabbage extracts using LC-MS/MS in the ESI negative mode coupled with the QuEChERS method. [ABSTRACT FROM AUTHOR]

Let F q be a finite field of characteristic two. We prove that for any given element a F q, there exists a primitive polynomial of degree n over F q with the m-th (0< m< n) coefficient S m= a when n=7, n is odd. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the 0,1 distribution in the highest level sequence ae-1 of primitive sequence over Z2e generated by a primitive polynomial of degree n. First we get an estimate of the 0,1 distribution by using the estimates of exponential sums over Galois rings, which is tight for e relatively small to n. We also get an estimate which is suitable for e relatively large to n. Combining the two bounds, we obtain an estimate depending only on n, which shows that the larger n is, the closer to 1/2 the proportion of 1 will be. [ABSTRACT FROM AUTHOR]