Catching two rabbits: adaptive real‐time support for embedded Linux

The trend of digital convergence makes multitasking common in many digital electronic products. Some applications in those systems have inherent real‐time properties, while many others have few or no timeliness requirements. Therefore the embedded Linux kernels, which are widely used in those devices, provide real‐time features in many forms. However, providing real‐time scheduling usually induces throughput degradation in heavy multitasking due to the increased context switches. Usually the throughput degradation becomes a critical problem, since the performance of the embedded processors is generally limited for cost, design and energy efficiency reasons. This paper proposes schemes to lessen the throughput degradation, which is from real‐time scheduling, by suppressing unnecessary context switches and applying real‐time scheduling mechanisms only when it is necessary. Also the suggested schemes enable the complete priority inheritance protocol to prevent the well‐known priority inversion problem. We evaluated the effectiveness of our approach with open‐source benchmarks. By using the suggested schemes, the throughput is improved while the scheduling latency is kept same or better in comparison with the existing approaches. Copyright © 2008 John Wiley & Sons, Ltd.     

A Synthesis of Multi-Precision Multiplication and Squaring Techniques for 8-Bit Sensor Nodes: State-of-the-Art Research and Future Challenges

Multi-precision multiplication and squaring are the performance-critical operations for the implementation of public-key cryptography, such as exponentiation in RSA, and scalar multiplication in elliptic curve cryptography (ECC). In this paper, we provide a survey on the multi-precision multiplication and squaring techniques, and make special focus on the comparison of their performance and memory footprint on sensor nodes using 8-bit processors. Different from the previous work, our advantages are in at least three aspects. Firstly, this survey includes the existing techniques for multiprecision multiplication and squaring on sensor nodes over prime fields. Secondly, we analyze and evaluate each method in a systematic and objective way. Thirdly, this survey also provides suggestions for selecting appropriate multiplication and squaring techniques for concrete implementation of public-key cryptography. At the end of this survey, we propose the research challenges on efficient implementation of the multiplication and the squaring operations based on our observation.     

Robust integrated shift register circuit over clock noises for in‐cell touch applications

This paper proposes an integrated shift register circuit for an in‐cell touch panel that is robust over clock noises. It is composed of 10 thin film transistors and 1 capacitor, and the time division driving method is adopted to prevent the negative effect of display signals on the touch sensing. Two pre‐charging nodes are employed for reducing the uniformity degradation of gate pulses over time. In particular, the proposed circuit connects a drain of the first pre‐charging node's pull‐up thin film transistor (TFT) to the positive supply voltage instead of clock signals. This facilitates to lower coupling noises as well as to clock power consumption. The simulation program with an integrated circuit emphasis is conducted for the proposed circuit with low temperature poly‐silicon TFTs. The positive threshold voltage that shifts up to 12 V at the first pre‐charging pull‐up TFT can be compensated for without the uniformity degradation of gate pulses. For a 60‐Hz full‐HD display with a 120‐Hz reporting rate of touches, the clock power consumption of the proposed gate driver circuit is estimated as 7.13 mW with 160 stages of shift registers. In addition, the noise level at the first pre‐charging node is lowered to ?28.95 dB compared with 2.37 dB of the previous circuit.     

Positioning control of an underwater robot with tilting thrusters via decomposition of thrust vector

Positioning control of an underwater robot is a challenging problem due to the high disturbances of ocean flow. To overcome the high disturbance, a new underwater robot with tilting thrusters was proposed previously, which can compensate for disturbance by focusing the thrusting force in the direction of the disturbance. However, the tilting motion of the thrusters makes the system nonlinear, and the limited tilting speed sometimes makes the robot unstable. Therefore, an optimized controller is necessary. A new positioning controller is proposed for this robot using a vector decomposition method. Based on the dynamic model, the nonlinear force input term of the tilting thrusters is decomposed in the horizontal and vertical directions. Based on the decomposition, the solution is determined by a pseudo-inverse and null-space solution. Using the characteristics of the decomposed input matrix, the final solution can be found by solving a simple second-order algebraic equation to overcome the limitations of the tilting speed. The positioning was simulated to validate the proposed controller by comparing the results with a switching-based controller. Tracking results are also presented. In future work, a high-level control strategy will be developed to take advantage of the tilting thrusters by focusing the forcing direction toward the disturbance with a limited stability margin.

     

Run-to-run control of inductively coupled C2F6 plasma etching of SiO2: Construction of a numerical process with a computational fluid dynamics code

A numerical process to simulate SiO₂ dry etching with inductively coupled C₂F₆ plasmas has been constructed using a commercial CFD code as a first step to design a run-to-run control system. The simulator was found to reasonably predict the reactive ion etching behavior of C₂F₆ plasmas and used to investigate the effects of plasma operating variables on the etch rate and uniformity. The relationship between the operating variables and the etching characteristics was mathematically modeled through linear regression for future run-to-run control system design.     

Preparation of bao-pbo-nd2o3-tio2 powders by hydrothermal synthesis

Homogeneous and nano-sized BPNT [(Ba_1-xPb_x)Nd₂Ti₅O₁₄] powders were prepared under various hydrothermal conditions. Crystallinity and homogeneity of the synthetic powders were investigated. The microwave dielectric properties of the filters prepared with hydrothermal powders were compared with those of the filters prepared with conventional powders. The microwave dielectric properties of the filter prepared with the hydrothermal powders were also better than those of the filter manufactured with the conventional powders. The dielectric constant, quality constant and temperature coefficient of resonance frequency of hydrothermally prepared filter under optimum condition and measured at 3.5 GHz around were about 93, 6067 and 0 ppm/°C, respectively.     

A procedural framework for dynamic changes of human interactions in knowledge intensive services

The knowledge intensive service processes should be managed in a human-oriented way since humans who naturally undertake complex operations of an intellectual nature in the processes are the most valuable resources. The most fundamental nature of human work is collaborative and dynamic. Humans interact and communicate with each other to accomplish their jobs in the process. To help them to work together, a strong representation of the process should be provided to facilitate them to clearly understand who they should interact with and what activities need to be performed. For the clear representation, Human Interaction Management (HIM), which has been suggested to comprehensively support human work, adopts a role-based approach to process modeling. It, however, tends to hide elements of interactions although the collaborative human interaction is one of the most fundamental nature of human work. To remedy this problem, a state-driven modeling approach to human interactions was presented. It clearly visualizes the interactions so that humans can be guided through it. However, they do not just follow the previously defined sequence of activities, but continuously work out how they are going to proceed from now on according to the state of things they encounter throughout the life of the work. To fully support the dynamic nature of human work, human interactions should be flexibly managed. Therefore, this paper presents a framework for the flexible management of human interactions. The framework provides a capability to flexibly manage the interactions in a decentralized way by allowing interaction participants to dynamically change the involved interaction based on the continuous negotiation of how to achieve the ultimate goal of the interaction. It will be a basis for realization of decentralized management of human interactions in knowledge intensive service processes.     

Development of environmentally responsive hydrogels with metal affinity behavior

This work describes initial efforts to incorporate affinity ligands within an environmentally responsive hydrogel. Metal affinity ligands were chosen as model affinity groups and thermally responsive N‐isopropyl acrylamide/acrylamide copolymers were used as the base hydrogels. The ? NH₂ group of the acrylamide serves as a reactive group for functionalization with metal affinity ligands. The gels were synthesized by free radical polymerization and Cu²⁺ was bound to the gel via 1,4‐butanediol diglycidyl ether (BDE) as a linker and iminodiacetic acid (IDA) as a chelating ligand. The base acrylamide gels were also functionalized with metal affinity ligands to allow for comparison with thermally responsive affinity gels. The results show the effectiveness of this technique for both these types of gels, and an improved method to immobilize metal affinity groups on to thermally sensitive N‐isopropyl acrylamide gels was also developed. It was seen that the yields for the reaction with BDE decreased with increased reaction time in both kinds of gels, whereas reaction with IDA showed a decrease in yields with increase in temperature for N‐isoporpyl acrylamide gels and increase in yields for acrylamide gels. Further techniques were developed to overcome diffusional resistances and stresses in the thermally responsive N‐isopropyl acrylamide gels so as to improve the distribution of Cu²⁺ ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Challenges of Raman Amplification

Raman amplifiers are often regarded as a typical example of technologies rapidly developed in the midst of turmoil created by the so-called wavelength division multiplexing (WDM) bubble. Indeed, Raman amplifiers turned out to be technically very attractive in all the aspects of capacity, reach, and bit rate. Even though Raman amplifiers are actually being deployed into systems in commercial service, the practical issues, such as cost, reliability and safety, are yet to be further discussed, particularly for the configuration of distributed amplification. After summarizing the advantages of Raman amplification and reviewing pump laser technologies, this paper will highlight ongoing efforts on practical issues, which include reliability and safety issues of fiber under high-power operations. Finally, it is concluded that by overcoming the above-mentioned practical issues, Raman amplification will stay as a key technology for future optical communications because of its compelling unique advantages.