儿童视角下“小学加法算理”教学的实施策略

小学数学从它的前身＂小学堂算术＂诞生之日起,就将计算列为首要的学习任务。《全日制小学算术教学大纲（草案）》明确提出：＂培养学生正确地、迅速地进行四则运算的能力,正确地解答应用题的能力,以及具有初步的逻辑推理能力和空间观念。＂由此开始,计算能力成为小学算术（数学）＂四大能力＂之首,要求也达到了顶峰。算理理解是学生计算能力提升的核心要素。算理,从字面上理解,即为运算的原理或道理,是解决问题的操作程序,解决＂为什么这样算＂的问题,学生只有理解了计算中的道理,才能够理解和掌握计算方法,才能正确、迅速地运算。下面结合多年教学实践,就如何促进学生对算理的深层理解和算法的切实把握谈一些做法。

A Reconfigurable Block Cryptographic Processor Based on VLIW Architecture

An Efficient and flexible implementation of block ciphers is critical to achieve information security processing.Existing implementation methods such as GPP,FPGA and cryptographic application-specific ASIC provide the broad range of support.However,these methods could not achieve a good tradeoff between high-speed processing and flexibility.In this paper,we present a reconfigurable VLIW processor architecture targeted at block cipher processing,analyze basic operations and storage characteristics,and propose the multi-cluster register-file structure for block ciphers.As for the same operation element of block ciphers,we adopt reconfigurable technology for multiple cryptographic processing units and interconnection scheme.The proposed processor not only flexibly accomplishes the combination of multiple basic cryptographic operations,but also realizes dynamic configuration for cryptographic processing units.It has been implemented with0.18μm CMOS technology,the test results show that the frequency can reach 350 MHz.and power consumption is 420 mw.Ten kinds of block and hash ciphers were realized in the processor.The encryption throughput of AES,DES,IDEA,and SHA-1 algorithm is1554 Mbps,448Mbps,785 Mbps,and 424 Mbps respectively,the test result shows that our processor's encryption performance is significantly higher than other designs.

On the Isolation Property over a Database Domain

The authors consider relational databases organized over an ordered domain with some additional relations - a typical example is the ordered domain of rational numbers together with the operation of addition. In the focus of our study are the FO （first-order） queries that are invariant under order-preserving permutations-such queries are called order-generic. It was discovered that for some domains order-generic FO queries fail to express more than pure order queries. The collapse result theorem was proved for locally genetic queries over a linearly ordered domain with the Pseudo finite Homogeneity Property （or / and the Isolation Property） by Belegradek et al.. Here the authors consider a circularly ordered domain and prove the collapse result theorem over a quasi circularly minimal domain.

A DIGITAL SIGNATURE-BASED VISUAL CRYPTOGRAPHY SCHEME FOR IMAGE DISCRIMINATION AND MANAGEMENT

Visual cryptography is a cryptographic technique which emerges in the information security domain in recent years. Each of the sharing sub-keys may be a stochastic noise image or a significative image with no information on the original key. But a mass of sub-keys have to be saved actually, which faces the problem of inconvenient discrimination and management. This paper presents a visual cryptography scheme based on the digital signature for image discrimination and management, applying the digital signature and the time-stamp technology to the visual cryptography scheme. The scheme both solves the problem on the storage and management of the sharing sub-keys, increases the verification of image contents, thus enhances the validity of storage and management without security effect.

A simulation of diesel hydrotreating process with real component method

Computer simulation is a good guide and reference for development and research on petroleum refining processes. Traditionally, pseudo-components are used in the simulation, in which their physical properties are estimated by empirical relations and cannot be associated with actual chemical reactions, as no molecular structure is available for pseudo-components. This limitation can be overcome if real components are used. In this paper, a real component based method is proposed for the simulation of a diesel hydrotreating process by using the software of Unisim Design. This process includes reaction units and distillation units. The chemical reaction network is established by analyzing the feedstock. The feedstock is characterized by real components, which are obtained based on true boiling point curve. Simulation results are consistent with actual data.

大道至简 以简驭繁——加法的本质是数数

在四则运算中，加法是最基本的运算。自然的加法运算是由最原始的“＋1”逐步复合而得到的。“＋1”的复合是皮亚诺自然数公理定义的核心，其本质是用有限去把握无限。加法的本质是数数，“＋1”的复合可以作为解释10以内加法的算理依据。把加法理解成“＋1”的复合，其基本思想是利用运算步骤将复杂的问题分解成许多简单的部分，这可以理解为现代数学的算法机械化思想。

MRT-LBM-based numerical simulation of seepage flow through fractal fracture networks

The study on seepage flow passing through single fractures is essential and critical for understanding of the law of seepage flow passing through fracture networks and the coupling mechanisms of seepage field and stress field in rock masses.By using the fractal interpolation to reconstruct a natural coarse fracture,as well as taking into account the microstructure of the fracture,the numerical simulation of seepage flow passing through the coarse fractures with two distinct vertical scaling factors is conducted based on the MRT-LBM model of the lattice Boltzmann method.Then,after obtaining the length of the preferential flow pathway,the permeability of the two kinds of fractures is estimated respectively.In view of difficulties in locating the preferential flow pathway of natural fracture networks,by numerical tests a transect permeability weighted algorithm for estimating the fracture network permeability is proposed.The algorithm is not specific to one or more particular preferential flow pathways,but considers the contribution of each section to hinder the fluid passing through the medium.In order to apply the new algorithm,by capturing the structure of fracture networks based on the image-processing technique,the numerical simulations of seepage flow passing through two groups of natural fracture networks is carried out,the permeability is forecasted and the partial flows are reproduced for both cases.It is found that the preferential flow pathway emerges at the beginning of evolution,then is strengthened subsequently,and finally reaches a steady status.Furthermore,by using the proposed method some details on local flow can be clearly observed such as backflows and vortices at local branches can exist simultaneously and so forth,suggesting the validness of the proposed method for multiscale simulations of seepage flow.

Orthogonal transformation operation theorem of a spatial universal uniform rotating magnetic field and its application in capsule endoscopy

According to the anti-phase sine current superposition theorem, the orientation, the magnetic flux density, the angular speed and the rotational direction of the spatial universal rotating magnetic field (SURMF) can be controlled within the tri-axial orthogonal square Helmholtz coils (TOSHC). Nevertheless, three coupling direction angles of the normal vector of the SURMF in the Descartes coordinate system cannot be separately controlled, thus the adjustment of the orientation of the SURMF is difficult and the flexibility of the robotic posture control is restricted. For the dimension reduction and the decoupling of control variables, the orthogonal transformation operation theorem of the SURMF is proposed based on two independent rotation angular variables, which employs azimuth and altitude angles as two variables of the three-phase sine current superposition formula derived by the orthogonal rotation inverse transformation. Then the unique control rules of the orientation and the rotational direction of the SURMF are generalized in each spatial quadrant, thus the scanning of the normal vector of the SURMF along the horizontal or vertical direction can be achieved through changing only one variable, which simplifies the control process of the orientation of the SURMF greatly. To validate its feasibility and maneuverability, experiments were conducted in the animal intestine utilizing the innovative dual hemisphere capsule robot (DHCR) with active and passive modes. It was demonstrated that the posture adjustment and the steering rolling locomotion of the DHCR can be realized through single variable control, thus the orthogonal transformation operation theorem makes the control of the orientation of the SURMF convenient and flexible significantly. This breakthrough will lay a foundation for the human-machine interaction control of the SURMF.