Efficient multiuser detector based on box-constrained deregularization and its FPGA design

Multiuser detection can be described as a quadratic optimization problem with binary constraint. Many techniques are available to find approximate solution to this problem. These tech- niques can be characterized in terms of complexity and detection performance. The ＂efficient frontier＂ of known techniques include the decision-feedback, branch-and-bound and probabilistic data association detectors. The presented iterative multiuser detection technique is based on joint deregularized and box-constrained so- lution to quadratic optimization with iterations similar to that used in the nonstationary Tikhonov iterated algorithm. The deregulari- zation maximizes the energy of the solution, this is opposite to the Tikhonov regularization where the energy is minimized. However, combined with box-constraints, the deregularization forces the solution to be close to the binary set. We further exploit the box- constrained dichotomous coordinate descent （DCD） algorithm and adapt it to the nonstationary iterative Tikhonov regularization to present an efficient detector. As a result, the worst-case and aver- age complexity are reduced down to K28 and K2~ floating point operation per second, respectively. The development improves the ＂efficient frontier＂ in multiuser detection, which is illustrated by simulation results. Finally, a field programmable gate array （FPGA） design of the detector is presented. The detection performance obtained from the fixed-point FPGA implementation shows a good match to the floating-point implementation.

Surface Graft Copolymerization of Acrylic Acid onto Corona Treated Cotton Fabric

Acrylic acid was grafted onto the surface of cotton fabric after being short time treated by corona-discharge inair in the presence of initiator.The means of gas-phaseSO2 derivatization was used along with ESCA to deter-mine corona-discharge-induced-hydroperoxidegroups on the surface.The content of hydroperoxideshows a maxmium value at 15 sec.of corona-dischargetime.Effect of corona treatment time and various con-centration initlator on graft yield was studied.The addit-ion of initiator increases the graft yield.Acceleratedgraft with an increase in the concentration of Mohr’s saltshows that peroxide groups on the corona treated cottonfabric initiate graft copolymerization.

杂谈Izationization

1985年,Quirk等在其名著《英语语法大全》中指出:“滥用或别出心裁地使用-ize词项常常因语体原因而受到批评”(p.2157)。 但是近年来,形容词/名词+iz(e)+ation之风反而日益盛行,以至在美国英语中出现一个贬义的新词:Izationization,意谓"the creation of lengthy nouns out of shorter words by adding-ization”,姑且译作“-ization化或力口‘化’风”。 错综复杂的中东政局,尤其是刚刚偃旗息鼓的海湾战争,又使这个-ization家族的几名成员频频见诸报端。 Lebanonization/Lebanization,黎巴嫩化,就是一例。

A TRUST REGION ALGORITHM FOR A CLASS OF NONLINEAR OPTIMIZATION

This paper presents a trust region algorithm for nonlinear optimization with linear inequality constraints. The global convergence of the algorithm is proved. Local quadratic convergence is obtained for a strong local minimizer.

An inductorless CMOS programmable-gain amplifier with a>3 GHz bandwidth for60 GHz wireless transceivers

An inductorless wideband programmable-gain amplifier （PGA） for 60 GHz wireless transceivers is presented. To attain wideband characteristics, a modified Cherry-Hooper amplifier with a negative capacitive neu- tralization technique is employed as the gain cell while a novel circuit technique for gain adjustment is adopted; this technique can be universally applicable in wideband PGA design and greatly simplifying the design of wideband PGA. By cascading two gain cells and an output buffer stage, the PGA achieves the highest gain of 30 dB with the bandwidth much wider than 3 GHz. The PGA has been integrated into one whole 60 GHz wireless transceiver and implemented in the TSMC 65 nm CMOS process. The measurements on the receiver front-end show that the re- ceiver front-end achieves an 18 dB variable gain range with a 〉 3 GHz bandwidth, which proves the proposed PGA achieves an 18 dB variable gain range with a bandwidth much wider than 3 GHz. The PGA consumes 10.7 mW of power from a 1.2-V supply voltage with a core area of only 0.025 mm2.

Deformation Behavior of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd Alloy in β/Quasi-β Forging Process

The hot deformation behavior of Ti 5.6Al-4.8Sn-2.0Zr-1.0Mo 0.35Si 0.85Nd alloy in β/quasi-β forging process was studied using isothermal compression tests over temperature range from 1040℃ to 1 100 ℃ and strain rates form 0. 001 s-1 to 70 s -1. The results show that the flow stress and mierostrueture are sensitive to thermomechanical parameters. The processing maps based on the dynamic materials model at strain of 0.3 and 0.7 were established. The optimum deformation thermomechanical parameters at a strain of 0.7 have two regions that exhibit the peak of power dissipation efficiency. One is the region of 1062-1100 ℃ and 10- 3 10-1.5 s -1 ; and another which represents dynamic recrystallization is 1040-1045 ℃ and 10-1.8 10- 0.5 s -1. The instable region is located where the strain rate is larger than 1 s 1 which corresponds to the mechanical instability.

Studies towards Bioinspired Synthesis of Hetidine-Type C20-Diterpenoid Alkaloids

Details of a biogenetically inspired strategy that led to the synthesis of the hetidine-type C20-diterpenoid alka- loid skeleton are reported in this paper. Key steps of our synthesis include a C-H oxidation to convert the atis- ine-type core to the ajaconine skeleton, as well as an aza-Prins cyclization that establishes the hetidine alkaloid skeleton. An unexpected heptacyclic framework bearing a unique tricyclo[3.3.1.02.7]nonane moiety has been ob- tained during our studies, which may represent a new type of C20-diterpenoid alkaloids yet to be discovered.