Measurement of nonlinear mechanical properties of PDMS elastomer

This paper presents the measurement of the nonlinear mechanical properties of polydimethylsiloxane (PDMS) elastomer based on the mixing ratio of base polymer to curing agent. Strip-type PDMS samples with different mixing ratios were prepared using a simple coating, curing, and cutting process. A cyclic uniaxial tension test with a fixed magnitude of applied strain and a single-pull-to-failure tension test were performed with a micro-tensile tester at room temperature.Our new finding is that when the PDMS is mixed with excessive curing agent, stress softening occurs and residual strain exists in cyclic tension tests when the magnitude of the applied strain increases. For the PDMS-05 samples, in which the mixing ratio of base polymer to curing agent was 5 to 1, there were large differences in the stresses for the same strain level under loading and unloading during the first cycle with a 100% fixed strain amplitude, but the softening effect of the stress in the PDMS dropped rapidly starting from the second cycle.Nonlinear mechanical Neo-Hookean, third-order Mooney, and second-order Ogden models of three different PDMS films were computed from the stress-strain data. The results showed that all models were preferable for the small strain region of PDMS compared with other models. In the nonlinear, large strain region, only the second-order Ogden model properly described the mechanical behavior of the PDMS, while the Neo-Hookean and third-order Mooney-Rivlin models were too stiff or flexible in the measurement range. The bulk modulus of PDMS increased with the amount of curing agent in it. Therefore, the second-order Ogden model is preferable for analyzing the PDMS structure over the entire measurement range. This could provide reasonable mechanical models of PDMS for rapid computational prototyping and for designing active and passive components from PDMS.     

Biometric bits extraction through phase quantization based on?feature level fusion

Biometric bits extraction has emerged as an essential technique for the study of biometric template protection as well as biometric cryptosystems. In this paper, we present a non-invertible but revocable bits extraction technique by means of quantizing the facial data from two feature extractors in the phase domain, which we coin as aligned feature-level fusion phase quantization (AFPQ). In this technique, we utilize helper data to achieve the revocability requirement of bits extraction. The feature averaging and remainder normalization technique are integrated with the helper data to reduce feature variance within the same individual and increase the distinctiveness of bit strings of different individuals to achieve good recognition performance. A scenario in which the system is compromised by an adversary is also considered. As a generic technique, AFPQ can be easily extended to multiple different biometric modalities.     

部分响应连续相位调制信号在卫星移动信道中的误比特率性能分析

该文给出了组合卫星移动信道中采用差分相位检测(DPD)和最大比组合(MRC)的部分响应连续相位调制(PRCPM)信号的误比特率计算公式,并给出了有关数值计算结果。     

A signal-alignment theory in rolling-based lightwave transmissionsystems

A theory to support signal alignment in rolling-based lightwave transmission systems is developed. The theory originates from the transmission system environment, which consists of three basic building blocks-multiplexer, scrambler, and permuter. These building blocks are represented by mathematical operators, on the basis of which mathematical expressions of the whole transmission system become possible. The mathematical operators are directly translated into number operators which help detect and identify the received signals in the form of a table-the signal-detection table. The signal-detection tables play a central role in the signal-alignment theory, since any transmission system can be represented by its corresponding signal-detection table. The entries in the signal-detection tables are closely correlated so that the tables can be uniquely characterized by their corresponding characteristic expressions. Various types of signal-detection tables are examined, and solutions to align transmitted signals and to reduce signal-alignment time in rolling-based lightwave transmission systems are exemplified through scrambler-permuter configurations     

感应自加热重熔无铅焊料凸台的剪切失效模式

通过两次高频感应重熔制备了Cu焊盘上S n3．5Ag焊料和Sn3．0Ag0．5Cu焊料凸台,并进行了120℃下的老化试验以及老化试件的剪切强度试验,分析了不同老化时间下两种无铅焊料凸台的剪切断裂模式。焊料凸台的剪切载荷-位移曲线的特征以及对焊料凸台剪切断口的扫描电镜形貌分析结果表明,不同老化时间下无铅焊料凸台的剪切断裂表现为塑性、韧性和脆性三种断裂模式。对凸台焊料合金的组织以及界面观察结果表明,随老化时间不断生长的脆性金属间化合物层以及焊料组织粗大是致使断裂失效模式转变的根本原因。     

Comments on "A carry-free 54 b/spl times/54 b multiplier using equivalent bit conversion algorithm"

For original paper see ibid., vol. 36, no. 10, p. 1538-1545 (Oct. 2001). In the aforementioned paper by Kim et al., a multiplier is presented which produces the result in radix-2 signed-digit representation. It is claimed that this representation can be converted into conventional magnitude representation by an algorithm which has no carry propagation. To the commenters this algorithm seems incorrect. The critical situation is a string which consists of a sequence of zeros followed by a -1; in such a case a carry is needed and the algorithm proposed is deemed incorrect. Consequently, it is pointed out that the proposed algorithm produces a correct multiplication result in conventional magnitude representation only if the signed-digit string does not have a sequence of 0's followed by a -1. The commenters show a multiplication example using the proposed conversion algorithm in which this situation occurs.     

Performance analysis of error propagation effects in the DFE for ATSC DTV receivers

The paper analyzes the error propagation phenomenon in the decision feedback equalizer (DFE) for the receivers of Advanced Television Systems Committee (ATSC) digital television (DTV) and presents the performance upper-limits of the DFE by comparing various error propagation cases and the no-error propagation case. As one approach to the performance limit, we consider a blind DFE, adopting a trellis decoder with a trace-back depth of 1 as a decision device. Through simulation, we show how much the DFE performance in ATSC DTV receivers is affected by error propagation. We found that while blind equalization is preferable to decision-directed (DD) equalization at signal-to-noise ratio (SNR) values less than 18 dB, DD equalization is superior to blind equalization at SNR values greater than 18 dB. In addition, symbol error rate curves quantitatively show that the performance difference in the DFE caused by error propagation becomes clearer at the trellis decoder following the DFE. The analysis results presented are very informative for developing equalization algorithms for ATSC DTV receivers.     

Analysis of large-signal dynamic characteristics of 10-Gb/s tunable distributed Bragg reflector lasers integrated with electroabsorption modulator and semiconductor optical amplifier based on the time-dependent transfer matrix method

We investigate large-signal dynamic characteristics of tunable distributed Bragg reflector (DBR) lasers with different structures. Because of high chirp and complex structures of tunable DBR lasers, it is difficult to accurately analyze large signal chirp and output pulse shapes with analytical models. Therefore, we apply a numerical model based on the time-dependent transfer matrix method to tunable DBR lasers integrated with electroabsorption modulator (EAM) and semiconductor optical amplifier (SOA). Using this model, we find a suitable /spl alpha/-parameter range in the Bragg grating section (/spl alpha//sub Bragg/-parameter) that produces the tolerable wavelength chirp while maintaining a proper tuning range. To employ the tunable lasers in wavelength division multiplexed networks and improve flexibility of the networks, the tunable lasers should have high output power and low wavelength chirp. According to our simulation results, the EAM section had better be located in between SOA and DBR laser sections to obtain high output power and low wavelength chirp.     

470-MHz–698-MHz IEEE 802.15.4m Compliant RF CMOS Transceiver

This paper proposes an IEEE 802.15.4m compliant TV white-space orthogonal frequency-division multiplexing (TVWS)-(OFDM) radio frequency (RF) transceiver that can be adopted in advanced metering infrastructures, universal remote controllers, smart factories, consumer electronics, and other areas. The proposed TVWS-OFDM RF transceiver consists of a receiver, a transmitter, a 25% duty-cycle local oscillator generator, and a delta-sigma fractional-N phase-locked loop. In the TV band from 470 MHz to 698 MHz, the highly linear RF transmitter protects the occupied TV signals, and the high-Q filtering RF receiver is tolerable to in-band interferers as strong as −20 dBm at a 3-MHz offset. The proposed TVWS-OFDM RF transceiver is fabricated using a 0.13-μm CMOS process, and consumes 47 mA in the Tx mode and 35 mA in the Rx mode. The fabricated chip shows a Tx average power of 0 dBm with an error-vector-magnitude of < 3%, and a sensitivity level of −103 dBm with a packet-error-rate of < 3%. Using the implemented TVWS-OFDM modules, a public demonstration of electricity metering was successfully carried out.     

Reactive Sintering of Copper Nanoparticles Using Intense Pulsed Light for Printed Electronics

Most commercial copper nanoparticles are covered with an oxide shell and cannot be sintered into conducting lines/films by conventional thermal sintering. To address this issue, past efforts have utilized complex reduction schemes and sophisticated chambers to prevent oxidation, thereby rendering the process cost ineffective. To alleviate these problems, we demonstrate a reactive sintering process using intense pulsed light (IPL) in the present study. The IPL process successfully removed the oxide shells of copper nanoparticles, leaving a conductive, pure copper film in a short period of time (2 ms) under ambient conditions. The in situ copper oxide reduction mechanism was studied using several different experiments and analyses. We observed instant copper oxide reduction and sintering through poly(N-vinylpyrrolidone) functionalization of copper nanoparticles, followed by IPL irradiation. This phenomenon may be explained by oxide reduction either via an intermediate acid created by ultraviolet (UV) light irradiation or by hydroxyl (-OH) end groups, which act like long-chain alcohol reductants.