基于PT2258的AV5.1多声道音响控制系统

介绍基于PT2258的红外遥控AV5.1音响控制系统的软硬件设计。该设计以功能强大的六声道音量控制集成电路PT2258,辅以PIC16C56微控制器,对声道进行选择输入、集中控制,软硬件设计均采用模块化结构的设计思想,使得AV5.1音响控制系统具有使用方便、性价比高等特点。

为XingMPEG解压缩软件增加左右声道控制

Xing MPEG解压缩软件是美国Xing Technology Corporation公司在1995年专为软件播放VCD影碟而开发的,是当今多媒体计算机应用领域中供用户观看VCD的十分优秀的解压缩软件。由于它可为用户省去购买解压硬卡所需的上千元开支,并且还可节省主板上一个宝贵的扩展插槽,故而目前一直被人们广泛使用。它不仅为无解压卡的用户提供了观看VCD的可能,而且还具有一般解压卡所没有的功能。比如:画面可任意缩放以及画面可随时捕捉供用户以BMP图像文件格式保存下来或通过打印机打印出来等功能。为此。

新声SAM-200/SAD-200前后级七声道影音控制中心

SAD—200/SAM—200是新声音响继SAV—3290、SAV—1150之后又一倾力之作,如果说SAV—3290、SAV—1150让国产AV功放受到众人的认可和关注;那么SAD—200/SAM—200及其姊妹精品SAV—300完全七声道功放定将改变人们对国产AV器材技术含金量的质疑态度,毫无疑问,这样的前后级在国内只有用“绝无仅有”来说明才恰当。

Strength and damage evolution mechanism of rock mass with holes under cyclic loading

The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic loading, elucidates the acoustic emission (AE) characteristics and their spatial evolution, and establishes the interrelation among AE, stress, strain, time, and cumulative damage. The results reveal that the rock mass with holes and the intact rock mass show softening and hardening characteristics after cyclic loading. The plastic strain of the rock mass with holes is smaller than that of the intact rock mass, and the stress −strain curve shows hysteresis characteristics. Under uniaxial compression, the pore-bearing rock mass shows the characteristics of higher ringing count, AE energy, b-value peak, and more cumulative ringing count in the failure stage, while it shows lower characteristics under cyclic action. At the initial stage of loading, compared with the intact rock mass, the pore-containing rock mass shows the characteristics of a low b-value. The AE positioning and cumulative damage percentage are larger, and the AE positioning is denser around the hole. The specimen with holes is mainly shear failure, and the complete specimen is mainly tensile shear failure.

Application and optimization design of non-obstructive particle damping-phononic crystal vibration isolator in viaduct structure-borne noise reduction

The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.

Hierarchical Code Assignment Algorithm and StateBased CDMA Protocol for UWSN

The characteristics of underwater acoustic channel such as long propagation delay and low bit rate cause the MAC(Medium Access Control) protocols designed for radio channels to be either inapplicable,or have low efficiency for UWSN(Underwater Sensor Network).We propose a hierarchical and distributed code assignment algorithm based on divisive probability function which can avoid conflict between spread codes with high probability,and provide a statebased MAC protocol for UWSN.Without RTS/CTS(Request To Send/Clear To Send) handshaking,each node maintains a neighbor table including state field,and packages are forwarded according to the state of the receiver,so it can avoid the interference caused by transmitting to a sending node in a half-duplex system and improve channel utilization.The design of power control minimizes the nearfar effect inherent in CDMA.Simulation results reveal that state-based CDMA protocol shows outstanding performance in throughput,delivery ratio and resource-consumption.

走近“非 Intel”800MHz FSB芯片组 VIA PT880、PT880和PT890技术前瞻

2003年已过去了一大半，Intel的帝国反击战也以800MHz FSB Pertium4处理器的推出而告一段落,Intel重拳出击的结果是——第三方Pentium4芯片组的不景气，市场上只有Intel的产品可选。然而这个格局很容易就被打破了——在AMD与nVIDIA联盟的压力下．Intel重新向VIA和SiS开放了800MHz FSB Pentium4处理器的授权,于是便有了VIA PT800、PT880和PT890等几款支持800MHz Pentium4处理器的芯片组诞生，然而它们究竟给我们带来了哪些不一样的技术特性，我们又能从中获得些什么呢？请和我们一起走进不属于Intel的800MHz Pentium4芯片组的世界。

马兰士“业余”技术拼盘SC-7S1赏析

随着新一代数字光碟SACD和DVD-Audio的问世，音响设备源头的声源质量有突破性的进展；而在音响设备终端的音箱方面，也出现了像B&w公司N800/S800这样性能和音质超群的录音室监听音箱；一时间令放大器显得有点落伍。作为放大器名厂的马兰士，尽管也在不断推出素质一流的各种放大器，但面对新形势，也感到了压力。