Optimized RTL Code Generation from Coarse-Grain Dataflow Specification for Fast HW/SW Cosynthesis

This paper presents a new methodology of automatic RTL code generation from coarse-grain dataflow specification for fast HW/SW cosynthesis. A node in a coarse-grain dataflow specification represents a functional block such as FIR and DCT and an arc may deliver multiple data samples per block invocation, which complicates the problem and distinguishes it from behavioral synthesis problem. Given optimized HW library blocks for dataflow nodes, we aim to generate the RTL codes for the entire hardware system including glue logics such as buffer and MUX, and the central controller. In the proposed design methodology, a dataflow graph can be mapped to various hardware structures by changing the resource allocation and schedule information. It simplifies the management of the area/performance tradeoff in hardware design and widens the design space of hardware implementation of a dataflow graph. We also support Fractional Rate Dataflow (FRDF) specification for more efficient hardware implementation. To overcome the additional hardware area overhead in the synthesized architecture, we propose two techniques reducing buffer overhead. Through experiments with some real examples, the usefulness of the proposed technique is demonstrated.

Chemical synthesis and electrochemical analysis of nickel cobaltite nanostructures for supercapacitor applications

Nickel cobaltite (NiCo₂O₄) films containing nanorods and nanoflakes are synthesized on indium tin oxide (ITO) substrates by a chemical bath deposition method and calcination process at 300 °C for 3 h. The NiCo₂O₄/ITO films are used as electrodes for supercapacitor applications, and electrochemical properties of the NiCo₂O₄ nanostructures are examined by cyclic voltammetry and charge-discharge experiments. NiCo₂O₄ nanorods exhibit the largest specific capacitance, with a value of 490 F g⁻¹at energy and power densities of 45 Wh kg⁻¹ and 2 kW kg⁻¹, respectively. This is significantly better than the performance of NiCo₂O₄ nanoflakes. Cycle-life tests show that the specific capacitance of NiCo₂O₄ is stable even after 1000 cycles, indicating its high potential for supercapacitor applications. The low cost and environmental friendliness of NiCo₂O₄ nanorods, coupled with its high supercapacitor performance, offer advantages over other transition metal oxides used for supercapacitors.     

DNA binding and unwinding by self-assembled supramolecular hetero-bimetallacycles

Two new tetracationic hetero-bimetallacycles were prepared from a bis-pyridine amide ligand and metal (Pd and Pt) acceptors. We found that both self-assembled hetero-bimetallacycles bind and unwind supercoiled DNA as established by photophysical and gel electrophoresis analyses, respectively.     

Influence of dehydrating agents on the oxidative carbonylation of methanol for dimethyl carbonate synthesis over a Cu/Y-zeolite catalyst

The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate(DMC) via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from CuCl_2·2 H_2O and the commercial NH_4-form of the Y type zeolite. The catalyst was characterized by X-ray fluorescence(XRF), N_2 adsorption(BET method), X-ray diffraction(XRD), and temperature-programmed desorption of ammonia(NH_3-TPD) to evaluate its Cu and Cl content, surface area, structure, and acidity. Reaction tests were carried out using an autoclave(batch reactor) for 18 h at 403 K and 5.5 MPa(2CH_3OH + 1/2O_2+CO?(CH_3O)_2CO + H_2O). The influence of various dehydrating agents(ZnO, MgO, and CaO) was examined with the aim of increasing the methanol conversion(X_(MeOH), MeOH conversion). The MeOH conversion increased upon addition of metal oxides in the order CaO MgO ZnO, with the DMC selectivity(SDMC) following the order MgO CaO ZnO. The catalysts and dehydrating agents were characterized before and after the oxidative carbonylation of methanol by thermogravimetric and differential thermogravimetric(TG/DTG), and XRD to confirm that the dehydration reaction occurred via the metal oxide(MO + H_2O → M(OH)_2). The MeOH conversion increased from 8.7% to 14.6% and DMC selectivity increased from 39.0% to 53.1%, when using the dehydrating agent CaO.     

Efficient hardware controller synthesis for synchronous dataflow graph in system level design

This paper concerns automatic hardware synthesis from data flow graph (DFG) specification in system level design. In the presented design methodology, each node of a data flow graph represents a hardware library module that contains a synthesizable VHDL code. Our proposed technique automatically synthesizes a clever control structure, cascaded counter controller, that supports asynchronous interaction with outside modules while efficiently implementing the synchronous dataflow semantics of the graph at the same time. Through comparison with previous works with some examples, the novelty of the proposed technique is demonstrated.     

Coordination Driven Self-Assembly and Anticancer Activity of Molecular Rectangles Containing Octahedral Ruthenium Metal Centers

The synthesis of new 2+2 metalla-rectangles via coordination driven self-assembly of octahedral Ru(II) based acceptors and amide donors is described. To evaluate their in vitro cytotoxic properties, preliminary biological assays were carried out for various human cancer cell lines, and our results show that the cytotoxicity level of 3 is comparable or even greater in the cases of SK-hep-1 and HCT-15 than that of the reference drug cisplatin.     

Tensile behavior of directionally solidified Ni3Al intermetallics with different Al contents and solidification rates

Despite the excellent high temperature mechanical properties of the Ni3Al intermetallic compound, its application is still limited due to its inherently weak grain boundary. Recent research advances have demonstrated that the tensile ductility can be enhanced by controlling the grain morphology using a directional solidification. In this study, a series of directional solidification experiments were carried out to increase both the tensile ductility and the strength of Ni₃Al alloys by arraying either the ductile phase of γ-Ni-rich dendrite fibers or the hard phase of β-NiAl dendrite fibers in the γ′-Ni₃Al matrix. The dendrite arm spacing could be controlled by the solidification rate, and the volume fraction of the γ or β phase could be altered by the Al content, ranging from 23 at.% to 27 at.%. With an increasing Al content, the γ dendritic microstructure was transformed into the β dendrite in the γ′ matrix, thereby reducing the tensile ductility by increasing the volume fraction of brittle β dendrites in the γ′ matrix. With an increasing solidification rate, the dendrite arm spacing decreased and the tensile properties of Ni₃Al varied in a complex manner. The microstructural evolution affecting the tensile behavior of directionally solidified Ni₃Al alloy specimens with different solidification rates and Al contents is discussed.     

Assumed model feedforward sliding mode control for a wheeled mobile robot with 3-DOF manipulator systems

In this paper, a three wheeled mobile platform with a 3-DOF manipulator was designed and its dynamic model has been constructed and a Sliding mode control (SMC) with the kinematic control is designed to follow the designed position trajectory for a mobile manipulator. Next, an assumed dynamic model of each system is used to design sliding mode controller in order to replace the modelbased control and adaptive estimation for unknown dynamic parameters. The stability of the proposed control scheme has been proved by Lyapunov theory. The effectiveness and accuracy of the proposed algorithm has been verified by simulations and practical experiments for the developed mobile manipulator system. And the simulation and experimental results have been compared to those of traditional PID algorithm to show the superiority of the proposed algorithm.

     

Barrier Lyapunov function-based model-free constraint position control for mechanical systems

In this article, a motion constraint control scheme is presented for mechanical systems without a modeling process by introducing a barrier Lyapunov function technique and adaptive estimation laws. The transformed error and filtered error surfaces are defined to constrain the motion tracking error in the prescribed boundary layers. Unknown parameters of mechanical systems are estimated using adaptive laws derived from the Lyapunov function. Then, robust control used the conventional sliding mode control, which give rise to excessive chattering, is changed to finite time-based control to alleviate undesirable chattering in the control action and to ensure finite-time error convergence. Finally, the constraint controller from the barrier Lyapunov function is designed and applied to the constraint of the position tracking error of the mechanical system. Two experimental examples for the XY table and articulated manipulator are shown to evaluate the proposed control scheme.

     

Frost formation on a plate with different surface hydrophilicity

The objectives of this study are to develop frost maps for two different surfaces having two different hydrophilic characteristics and to find ambient conditions associated with the formation of frost structures. Test samples with two different surfaces having dynamic contact angle (DCA) of 23° and 88° were installed in a wind tunnel and exposed to a humid airflow. Frost structure is observed with a visualization system in the operating conditions of household refrigerator: airflow temperature in the range of +10-20 °C, humidity in the range of 2.64-9.36 g/kg^′, Reynolds number in the range of 7000-17,000 and cold plate temperature in the range of −11.6 to −28.4 °C. As results of this study, frost structures are classified and frost maps are proposed for two different surface hydrophilicities. Surface with low DCA (23°) shows lower frost thickness and higher frost density than that with high DCA (88°). It was found that frost structures on surfaces with different DCA are similar. However, low DCA surface at low humidity provides 20-30% denser frost formation due to the shift of areas with different structures.