信息科学类最新新闻

信息科学类最新20条新闻

世界最大半导体公司之一的意法半导体日前宣布大中国区(中国大陆、香港和台湾)新总部在上海正式启用。新总部大楼位于上海闵行区紫竹科学园区，意法半导体公司首席运营官Alain Dutheil和公司副总裁兼大中国区总经理柯明远主持启用典礼，上海市及闵行区政府领导、意大利驻华总领事Massimo Roscigno先生和法国驻华总领事Jacques Torregrossa先生应邀参加典礼。

国内专业技术市场研究和推广机构北京华兴万邦管理咨询有限公司日前发布了08及09国际消费电子市场调研报告。这份面向行业人士免费提供的报告揭示，全球消费电子产品在产品定义、外观设计和功能应用等等方面正在发生巨大的变化。

由于任天堂的Wii以及苹果公司的iPhone取得了举世瞩目的成功，不少人想知道，在蜂窝手机以及其它消费电子产品中运动传感器承诺已久的增值是否即将到来。分析师表示，没有这么快。尽管基于微机电系统(MEMS)的传感器的价格已经快速下滑。

Maxim推出一款集成了高效负电荷泵、完全差分桥式音频放大器和2路低噪声低压差(LDO)电流调节器的白光LED (WLED)驱动器MAX8821。优异的性能和高集成度使MAX8821理想用于蜂窝电话、智能电话、PDA和便携式媒体播放器等每个毫安时的电池寿命都非常重要、且PCB空间受限的应用。

问：何谓单片机编程的可视化？答：可视化编程就是提供给用户可视化的器件模块配置界面使用户在不用关心具体器件工作原理和设置

So the big news of the midnight is that Google has launched their application cloud service.via Mashable

In the case of the need of extraordinary security, Kirchhoff-loop-Johnson-(like)-noise ciphers can easily be integrated on existing types of digital chips in order to provide secure data communication between hardware processors, memory chips, hard disks and other units within a computer or other data processor system. The secure key exchange can take place at the very first run and the system can renew the key later at random times with an authenticated fashion to prohibit man-in-the-middle attack. The key can be stored in flash memories within the communicating chip units at hidden random addresses among other random bits that are continuously generated by the secure line but are never actually used. Thus, even if the system is disassembled, and the eavesdropper can have direct access to the communication lines between the units, or even if she is trying to use a man-in-the-middle attack, no information can be extracted. The only way to break the code is to learn the chip structure, to understand the machine code program and to read out the information during running by accessing the proper internal ports of the working chips. However such an attack needs extraordinary resources and even that can be prohibited by a password lockout. The unconditional security of commercial algorithms against piracy can be provided in a similar way.

In this paper we prove that for any infinite word W whose set of factors is closed under reversal, the following conditions are equivalent:

(I) all complete returns to palindromes are palindromes;

(II) P(n) + P(n+1) = C(n+1) - C(n) + 2 for all n, where P (resp. C) denotes the palindromic complexity (resp. factor complexity) function of W, which counts the number of distinct palindromic factors (resp. factors) of each length in W.

In this paper, we study combinatorial and structural properties of a new class of finite and infinite words that are 'rich' in palindromes in the utmost sense. A characteristic property of so-called "rich words" is that all complete returns to any palindromic factor are themselves palindromes. These words encompass the well-known episturmian words, originally introduced by the second author together with X. Droubay and G. Pirillo in 2001. Other examples of rich words have appeared in many different contexts. Here we present the first unified approach to the study of this intriguing family of words.

Amongst our main results, we give an explicit description of the periodic rich infinite words and show that the recurrent balanced rich infinite words coincide with the balanced episturmian words. We also consider two wider classes of infinite words, namely "weakly rich words" and almost rich words (both strictly contain all rich words, but neither one is contained in the other). In particular, we classify all recurrent balanced weakly rich words. As a consequence, we show that any such word on at least three letters is necessarily episturmian; hence weakly rich words obey Fraenkel's conjecture. Likewise, we prove that a certain class of almost rich words obeys Fraenkel's conjecture by showing that the recurrent balanced ones are episturmian or contain at least two distinct letters with the same frequency.

Lastly, we study the action of morphisms on (almost) rich words with particular interest in morphisms that preserve (almost) richness. Such morphisms belong to the class of "P-morphisms" that was introduced by A. Hof, O. Knill, and B. Simon in 1995.

We present constructions of Space-Time (ST) codes based on lattice coset coding. First, we focus on ST code constructions for the short block-length case, i.e., when the block-length is equal to or slightly larger than the number of transmit antennas. We present constructions based on dense lattice packings and nested lattice (Voronoi) shaping. Our codes achieve the optimal diversity-multiplexing tradeoff of quasi-static MIMO fading channels for any fading statistics, and perform very well also at practical, moderate values of signal to noise ratios (SNR). Then, we extend the construction to the case of large block lengths, by using trellis coset coding. We provide constructions of trellis coded modulation (TCM) schemes that are endowed with good packing and shaping properties. Both short-block and trellis constructions allow for a reduced complexity decoding algorithm based on minimum mean squared error generalized decision feedback equalizer (MMSE-GDFE) lattice decoding and a combination of this with a Viterbi TCM decoder for the TCM case. Beyond the interesting algebraic structure, we exhibit codes whose performance is among the state-of-the art considering codes with similar encoding/decoding complexity.

Partition functions, also known as homomorphism functions, form a rich family of graph invariants that contain combinatorial invariants such as the number of k-colourings or the number of independent sets of a graph and also the partition functions of certain "spin glass" models of statistical physics such as the Ising model.

Building on earlier work by Dyer, Greenhill and Bulatov, Grohe, we completely classify the computational complexity of partition functions. Our main result is a dichotomy theorem stating that every partition function is either computable in polynomial time or #P-complete. Partition functions are described by symmetric matrices with real entries, and we prove that it is decidable in polynomial time in terms of the matrix whether a given partition function is in polynomial time or #P-complete.

While in general it is very complicated to give an explicit algebraic or combinatorial description of the tractable cases, for partition functions described by a Hadamard matrices -- these turn out to be central in our proofs -- we obtain a simple algebraic tractability criterion, which says that the tractable cases are those "representable" by a quadratic polynomial over the field GF(2).

The entropy of an organism's capacity to supply energy through its circulatory system is 4/3 the entropy of the organism's energy requirements. Organisms appear to maximize entropy. The concept of entropy enables shorter derivations of some allometric equations, further evidence of the concept's utility. Entropy helps explain emergence in social, lexical, and biological networks.

A discrete model of pedestrian motion is presented that is implemented in the Floor field- and Agentbased Simulation Tool (F.A.S.T.) which has already been applicated to a variety of real life scenarios.

We present the definition of the logical framework TF, the Type Framework. TF is a lambda-free logical framework; that is, it does not include lambda-abstraction or product kinds. We give formal proofs of several results in the metatheory of TF, and show how it can be conservatively embedded in the logical framework LF: its judgements can be seen as the judgements of LF that are in beta-normal, eta-long normal form. We show how several properties, such as adequacy theorems for object theories and the injectivity of constants, can be proven more easily in TF, and then `lifted' to LF.

We suggest a method for holding a dictionary data structure, which maps keys to values, in the spirit of Bloom Filters. The space requirements of the dictionary we suggest are much smaller than those of a hashtable. We allow storing n keys, each mapped to value which is a string of k bits. Our suggested method requires nk + o(n) bits space to store the dictionary, and O(n) time to produce the data structure, and allows answering a membership query in O(1) memory probes. The dictionary size does not depend on the size of the keys. However, reducing the space requirements of the data structure comes at a certain cost. Our dictionary has a small probability of a one sided error. When attempting to obtain the value for a key that is stored in the dictionary we always get the correct answer. However, when testing for membership of an element that is not stored in the dictionary, we may get an incorrect answer, and when requesting the value of such an element we may get a certain random value. Our method is based on solving equations in GF(2^k) and using several hash functions. Another significant advantage of our suggested method is that we do not require using sophisticated hash functions. We only require pairwise independent hash functions. We also suggest a data structure that requires only nk bits space, has O(n2) preprocessing time, and has a O(log n) query time. However, this data structures requires a uniform hash functions. In order replace a Bloom Filter of n elements with an error proability of 2^{-k}, we require nk + o(n) memory bits, O(1) query time, O(n) preprocessing time, and only pairwise independent hash function. Even the most advanced previously known Bloom Filter would require nk+O(n) space, and a uniform hash functions, so our method is significantly less space consuming especially when k is small.

The problem of detecting the sparsity pattern of a k-sparse vector in R^n from m random noisy measurements is of interest in many areas such as system identification, denoising, pattern recognition, and compressed sensing. This paper addresses the scaling of the number of measurements m, with signal dimension n and sparsity-level nonzeros k, for asymptotically-reliable detection. We show a necessary condition for perfect recovery at any given SNR for all algorithms, regardless of complexity, is m = Omega(k log(n-k)) measurements. Conversely, it is shown that this scaling of Omega(k log(n-k)) measurements is sufficient for a remarkably simple ``maximum correlation'' estimator. Hence this scaling is optimal and does not require more sophisticated techniques such as lasso or matching pursuit. The constants for both the necessary and sufficient conditions are precisely defined in terms of the minimum-to-average ratio of the nonzero components and the SNR. The necessary condition improves upon previous results for maximum likelihood estimation. For lasso, it also provides a necessary condition at any SNR and for low SNR improves upon previous work. The sufficient condition provides the first asymptotically-reliable detection guarantee at finite SNR.

Avago(安华高科技)推出一款具备2.5A最高尖峰输出电流的新门极驱动光电耦合器产品ACPL-K312。新ACPL-K312成功地满足了低功耗需求，并具有高抗噪声能力和快速的IGBT开关切换能力，可以改善效率，非常适合IGBT/MOSFET门极驱动、交流和无刷直流电机以及开关式电源等应用。

ANADIGICS宣布推出新型AWT6309线性功率放大器(PA)。该放大器专为在1.7GHz频段运行的CDMA无线手机和数据设备而设计，旨在与高通(Qualcomm) CDMA2000和EVDO芯片组兼容。

第十六届中国国际广播电视信息网络展览会（CCBN2008）于2008年3月21-23日在北京中国国际展览中心举行。中天联科成功参加2007CCBN后，携中国首颗直播卫星ABS-S信道解调芯片AVL1108和世界上最先进的DVB-S2专用接收信道解调芯片AVL2108再次参与此次广电行业的盛会。

2008年4月17日至18日，深圳将举办CAN和CANopen技术培训暨高级研讨会， CiA（CAN in AUTOMATION）国际组织主席MR. ZELTWANGER将亲临负责培训。