邻苯二甲酸二异壬酯增塑剂在提高挤出效益方面的应用

重点探讨了邻苯二甲酸二异壬酯（DINP-S）在提高挤出效益方面的优越性，在典型的挤出加工条件下，DINP-S比DOP更能降低混合料的熔融粘度，这有助于降低口模压力，减少机械磨损或提高挤出生产率（高达21%），这种生产率的提高可在无须更改产品配方和生产工艺，无须额外固定投资，无须额外能耗，且保持产品品质的情况下实现。     

Electron Beam Irradiation to Recrosslink Devulcanized Sulfur Cured Rubber Blended Polypropylene

This study aims to investigate the effect electron beam (EB) irradiation on the polypropylene/devulcanized sulfur cured rubber (PP‐DVC) compound. The PP‐DVC compounds were compounded using twin‐screw extruder and then compression molded into required shapes before irradiation begins. The gel content of all irradiated PP‐DVC compounds gradually increased with higher irradiation dose indicated that the presence of DVC plays an important role in crosslinking enhancement. The mechanical properties of PP‐DVC compounds were observed marginally higher at low irradiation dosages (≤50 kGy). However, higher irradiation dosages up to 200 kGy cause adverse effect to the PP‐DVC compounds. In addition, the application of low irradiation dosage could enhance the dispersion of DVC particles at 20 phr composition in PP matrix. This also found that the scanning electron microscopy (SEM) observation where the DVC particles dispersed better in PP matrix compared to that of nonirradiated samples. Further increment in irradiation dosages up to 200 kGy reduced the crystallinity caused by chain scissoring process could rupture the crystalline structure in PP matrix. It was also found that the wavenumber of the C? H and CH₂ groups for irradiated samples reduced at high irradiation dosages due to the formation of carbonyl group. POLYM. ENG. SCI., 59:1017–1027, 2019. © 2019 Society of Plastics Engineers     

Multiple serial and parallel concatenated single parity-check codes

Single parity-check (SPC) codes are applied in both parallel and serial concatenated structures to produce high-performance coding schemes. The number of concatenations or stages, M, is increased to improve system performance at moderate-to-low bit-error rates without changing the overall code parameters (namely, code rate and code block length). Analytical bounds are presented to estimate the performance at high signal-to-noise ratios. The SPC concatenated codes are considered with binary phase-shift keying and with 16-quadrature amplitude modulation bit-interleaved coded modulation on the additive white Gaussian noise channel and the independent Rayleigh fading channel. Simulations show that the four-stage serial or parallel concatenated SPC codes can, respectively, outperform or perform as well as 16-state turbo codes. Furthermore, decoding complexity is approximately 9-10 times less complex than that of 16-state turbo codes. The convergence behavior of both serial and parallel concatenated SPC codes is also discussed.     

A +31.5 dBm CMOS RF Doherty Power Amplifier for Wireless Communications

A fully differential Doherty power amplifier (PA) is implemented in a 0.13-mum CMOS technology. The prototype achieves a maximum output power of +31.5 dBm with a peak power-added efficiency (PAE) of 36% (39% drain efficiency) with a GMSK modulated signal. The PAE is kept above 18% over a 10 dB range of output power. With a GSM/EDGE input signal, the measured peak output power while still meeting the GSM/EDGE mask and error vector magnitude (EVM) requirements is +25dBm with a peak PAE of 13% (PAE is 6% at 12 dB back-off). Instead of using a bulky lambda/4 transmission line, a passive impedance inverter is implemented as a compact lumped-element network. All circuit components are fully integrated on a single CMOS die except for an off-chip capacitor for output matching and baluns. The die size is 2.8times3.2mm² including all pads and bypass capacitors     

Approximation-based control of nonlinear MIMO time-delay systems

Approximation-based control is presented for a class of multi-input multi-output (MIMO) nonlinear systems in block-triangular form with unknown state delays. Neural networks (NNs) are utilized to approximate and compensate for unknown functions in the system dynamics, including the unknown bounds of the functions of delayed states. The use of a separation technique removes the need for any assumption on the function of delayed states, and allows the handling of multiple delays in each function of delayed states. By combining the use of Lyapunov-Krasovskii functionals and adaptive NN backstepping, the proposed control guarantees that all closed-loop signals remain bounded, while the outputs converge to a neighborhood of the desired trajectories. Simulation results demonstrate the effectiveness of the proposed scheme.     

WDM-PON Architectures With a Single Shared Interferometric Filter for Carrier-Reuse Upstream Transmission

We propose two novel wavelength-division-multiplexed passive-optical-network (WDM-PON) architectures where subcarriers are employed to transmit downstream data and optical carriers are reused for upstream transmission. Architecture I is designed for the situation where two short distribution fibers are available between the remote node (RN) and each optical network unit (ONU), whereas Architecture II is devised for the case where there is only one distribution fiber between the RN and each ONU. Both architectures use only one interferometric filter located at the RN to simultaneously separate all downlink optical carriers and subcarriers, leading to a considerable cost reduction in the implementation of the WDM-PONs. Separated optical carriers are then reused and injected into reflective semiconductor optical amplifiers as the uplink light sources, which eliminates the necessity of specific wavelength sources at the ONUs. The downstream subcarrier signals are directly detected using baseband receivers. Two multichannel upstream and downstream transmission experiments are carried out at 1.25 Gb/s using the proposed schemes. The impact of optical carrier-to-subcarrier ratio of downlink signal, Rayleigh-backscattering noise, and wavelength mismatch between laser source and filter on system performance is also investigated.     

集成工艺中叠片BGA阵列翘曲的几何非线性预测分析

对层叠芯片BGA(SDBGA)阵列进行了线性小变形和非线性大翘曲仿真。与实验测量结果相比,线性方法不能反映翘曲形态而非线性大变形仿真能够反映出这种翘曲。原因在于,在小变形假设下,线性仿真不能考虑变形之后横断面惯性矩的变化。而非线性仿真则不受此假设的影响。文中基于非线性特性分析、预测了在整个集成工艺中SDBGA阵列的翘曲。利用“弯曲交互作用”和“翘曲竞争”解释了SDBGA阵列的翘曲特性。通过与线性仿真结果的比较,量化了几何非线性对集成工艺中SDBGA块封装翘曲的影响。     

A 1.75-GHz highly integrated narrow-band CMOS transmitter withharmonic-rejection mixers

A highly integrated 1.75-GHz 0.35-μm CMOS transmitter is described. The I/Q modulator-based transmitter facilitates integration through the use of a unique mixer, termed a harmonic-rejection mixer, and a wide loop bandwidth phase-locked loop (PLL) for the RF synthesizer. The harmonic-rejection mixers are used to eliminate the need for a discrete IF filter and the use of a wide loop bandwidth PLL allowed for the complete integration of the synthesizers using low-Q components while achieving low phase noise. The entire transmit signal path from the digital-to-analog converters to the power amplifier, including two fully integrated frequency synthesizers, is integrated into a single-chip solution. The transmitter was tested with a testing buffer before the power amplifier (PA) and achieved less than 1.3° rms phase error when modulating a DCS-1800 GMSK signal. The prototype consumed 151 mA from a 3-V supply. A class-C PA, capable of driving 25 dBm off-chip, was included and the output was compared to the testing buffer with little change in the transmitter performance     

Priority nutritional concerns in Asia

The sustained economic growth and increasing economic stability in the Asian region over the last three decades have been accompanied by changing lifestyles leading to significant changes in the food and nutrition issues facing Asian countries. The chronic diseases associated with excessive consumption of nutrients, especially fat, are becoming increasingly apparent. At the same time, Asia has a disproportionate share of the malnutrition problem. Underweight and stunting remain significant problems in many Asian communities, and micronutrient deficiencies of iron, iodine, and vitamin A continue to afflict large population groups. Effective data collection and analysis are essential to formulate and implement intervention programs to address both sides of the changing nutrition scenario in Asia.