Comments on "Linear function observer for linear discrete-time systems"

Two alternative systematic algorithms are suggested to compute the matrixTnecessary to design a minimum-time linear function observer. The simplicity of these algorithms gives mole insight to the understanding of the observer structure. Furthermore, the computational effort required to obtain the matrixJis spared.     

Arterial embolization for radical tumor resection

Two contemporary measures, selective transarterial embolization (Almgard et al. 1973) and controlled hypotensive anesthesia (Davis et al. 1974), have been combined in an effort to reduce the risk of operative bleeding in a case of massive bone and muscle resection of a highly vascular carcinoma lesion in the proximal third of the femur. This approach may be helpful in such cases.     

Gamma-Irradiation and Storage Effects on Some Chemical Aspects of Carrots

Studies on chemical changes induced by gamma-irradiation at optimum dose of 75 krad in carrots were undertaken. Sugars, nitrogen, free amino acids, amino acids of alcohol insoluble solids, and pectin fractions were determined. The results indicate that the postharvest irradiation of carrots does not dramatically affect their chemical composition during storage. However, it was observed that storage time affected significantly the biochemical changes occurring in the constituents of carrots exposed to gamma-irradiation.     

Changes in serum potassium and blood glucose concentrations after trimethaphan administration in man

Blood glucose and serum potassium (K+) concentrations were measured before, during, and 60 minutes after operation in two groups of 10 patients during nitrous oxide/halothane/d-tubocurarine anesthesia for major orthopedic surgery. In the control group, arterial blood pressure was maintained within normal range, while in the study group trimethaphan camsylate was administered as an intravenous infusion (average, 218 mg.) to maintain a systolic blood pressure of 60 to 65 torr. In the normotensive group, blood glucose rose significantly during operation and early postoperatively and serum K+ was essentially unchanged. In the hypotensive group, trimethaphan caused a striking modification of surgically induced hyperglycemia, together with a small significant decrease in serum K+ intraoperatively. The observed increase in blood glucose is part of the autonomic response to surgical stress. Hormonal factors (growth hormone, cortisol and glucagon) may conceivably be involved. The decrease in serum K+ is probably caused by decreased hepatic glycogenolysis and attenuation of the suppressive effect of catecholamines on insulin release, both effects being secondary to the ganglionic blocking property of trimethaphan. These results indicate that trimethaphan, in contrast to other ganglionic blocking drugs, does not cause hypoglycemia and suggest that serum K+ concentration should be monitored whenever these drugs are used.     

Hybrids for finishing cotton fabric with durable handle performance

New poly(acrylic acid/epichlorohydrin) hybrids were prepared under different polymerization conditions and the proper hybrid was used as a stiffening agent or what may be called hand builder. The latter was incorporated in dimethyloldihydroxy ethylene urea (DMDHEU) finishing formulation and the onset of this on fabric performance as monitored by nitrogen content, wrinkle recovery angle, tensile strength, stiffness, dyeability, and oily stain release was studied. Durability of the new finish was also examined. Results disclose substantial improvement in fabric performance and imply that the hybrid in question acts as a durable hand builder through fixation via its hydroxyl groups within the DMDHEU finish which, in turn, is chemically bonded to cotton cellulose. Scanning electron microscopy of finished fabric revealed that this chemical bonding resulted in hybrid encapsulation, deposition and/or coating of fabric fibers.     

Synthesis,characterization, and thermal stability of novel wholly para-oriented aromatic poly(ether-amide-hydrazide)s bearing pendant groups and their corresponding poly(ether-amide-1,3,4-oxadiazole)s

Four novel wholly para-oriented aromatic poly(ether-amide-hydrazide)s containing various pendant groups on their aromatic rings were synthesized from p-aminosalicylic acid hydrazide (PASH) with an equimolar amount of either 4,4′-(1,4-phenylenedioxy)dibenzoyl chloride (1a), 4,4′-(2,5-tolylenedioxy)dibenzoyl chloride (1b), 4,4′-(2-tert-butyl-1,4-phenylenedioxy)dibenzoyl chloride (1c), or 4,4′-(2,5-biphenylenedioxy)dibenzoyl chloride (1d) via a low temperature solution polycondensation reaction. A polyamide-hydrazide without the ether and pendant groups, poly[4-(terephthaloylamino)salicylic acid hydrazide, PTASH, is also investigated for comparison. It was synthesized from PASH and terephthaloyl chloride by the same synthetic route. The polymer intrinsic viscosities ranged from 4.5 to 2.47 dlg⁻¹ in N,N-dimethyl acetamide (DMAc) at 30 °C and decreased with the introduction of the ether and pendant groups into the polymer. All the polymers were soluble in DMAc, N,N-dimethyl formamide (DMF), and N-methyl-2-pyrrolidone (NMP) and their solutions could be cast into flexible films with good mechanical strengths. Further, they exhibited a great affinity to water sorption. Their solubility and hydrophilicity increased with introduction of the ether and pendant groups into the polymer. The prepared polymers could be thermally cyclodehydrated under nitrogen atmosphere into the corresponding poly(ether-amide-1,3,4-oxadiazole)s approximately in the region of 300–450 °C. The introduction of the flexibilizing ether linkages and the pendant groups into the polymer improves the solubility of the resulting poly(ether-amide-1,3,4-oxadiazole)s compared to poly(amide-1,3,4-oxadiazole) free from these groups.     

Distributed opportunistic scheduling for MIMO underlay cognitive radio networks

Cognitive radio networks have emerged to improve the utilization of the scarce spectrum. In this paper, we propose a distributed resource allocation algorithm that allocates resources opportunistically to the secondary users in a multiple‐input multiple‐output environment. In order to reduce the complexity and cost, antenna selection schemes are employed to allow the secondary communication using a single radio frequency chain. The proposed algorithm is proved theoretically and using simulations, to give a performance very close to that of a centralized one with lower delay and overhead. Furthermore, we introduce two techniques for the proposed algorithm based on the allowable data rates referred to as limited and maximum rates. We derive closed‐form expression for the consumed power and tight upper bounds for the average throughput achieved by each technique. A comparison between the proposed techniques is also provided. Both simulations and analytical results show that the proposed algorithm achieves high throughput with low complexity. Moreover, the results show that the tightness of the bounds improves with the diversity order. Finally, the proposed techniques are compared with two suggested random schemes to investigate their effectiveness. Copyright © 2016 John Wiley & Sons, Ltd.     

Near-infrared spectroscopic analysis of the breaking force of extended-release matrix tablets prepared by roller-compaction: influence of plasticizer levels and sintering temperature

The aim of this study was to investigate the feasibility of near-infrared (NIR) spectroscopy for the determination of the influence of sintering temperature and plasticizer levels on the breaking force of extended-release matrix tablets prepared via roller-compaction. Six formulations using theophylline as a model drug, Eudragit® RL PO or Eudragit® RS PO as a matrix former and three levels of TEC (triethyl citrate) as a plasticizer were prepared. The powder blend was roller compacted using a fixed roll-gap of 1.5?mm, feed screw speed to roller speed ratio of 5:1 and roll pressure of 4?MPa. The granules, after removing fines, were compacted into tablets on a Stokes B2 rotary tablet press at a compression force of 7?kN. The tablets were thermally treated at different temperatures (Room Temperature, 50, 75 and 100?°C) for 5?h. These tablets were scanned in reflectance mode in the wavelength range of 400–2500?nm and were evaluated for breaking force. Tablet breaking force significantly increased with increasing plasticizer levels and with increases in the sintering temperature. An increase in tablet hardness produced an upward shift (increase in absorbance) in the NIR spectra. The principle component analysis (PCA) of the spectra was able to distinguish samples with different plasticizer levels and sintering temperatures. In addition, a 9-factor partial least squares (PLS) regression model for tablets containing Eudragit® RL PO had an r² of 0.9797, a standard error of calibration of 0.6255 and a standard error of cross validation (SECV) of 0.7594. Similar analysis of tablets containing Eudragit® RS PO showed an r² of 0.9831, a standard error of calibration of 0.9711 and an SECV of 1.192.     

Robust and Efficient OFDM Synchronization for FPGA-Based Radios

Orthogonal frequency division multiplexing (OFDM) is a popular modulation technique that can combat impulsive noise, is robust to multipath fading, is spectrally efficient, and can allow flexible allocation of spectrum. It has become a key standard in cognitive radio systems as well as an enabling technology for mobile data access systems. An OFDM receiver’s performance is heavily impacted by the accuracy of its symbol timing offset (STO) and carrier frequency offset (CFO) estimation. This paper proposes a novel OFDM synchronization method that combines robust performance with computational efficiency. FPGA prototyping is used to explore the trade-off between the number of computations to be performed and computation word length with respect to both synchronization performance and power consumption. Through simulation, the proposed method is shown to provide accurate fractional CFO estimation as well as STO estimation in a range of channels. In particular, it can yield excellent synchronization performance in the face of a CFO that is larger than many state-of-the-art synchronization implementations can handle. The system implementation demonstrates efficient resource usage and reduced power consumption compared with existing methods, and this is explored as a fine-grained trade-off between performance and power consumption. The result is a robust method suitable for use in low-power radios, enabling less precise analog front ends to be used.     

Virtualized Execution and Management of Hardware Tasks on a Hybrid ARM-FPGA Platform

Emerging hybrid reconfigurable platforms tightly couple capable processors with high performance reconfigurable fabrics. This promises to move the focus of reconfigurable computing systems from static accelerators to a more software oriented view, where reconfiguration is a key enabler for exploiting the available resources. This requires a revised look at how to manage the execution of such hardware tasks within a processor-based system, and in doing so, how to virtualize the resources to ensure isolation and predictability. This view is further supported by trends towards amalgamation of computation in the automotive and avionics domains, where such properties are essential to overall system reliability. We present the virtualized execution and management of software and hardware tasks using a microkernel-based hypervisor running on a commercial hybrid computing platform (the Xilinx Zynq). The CODEZERO hypervisor has been modified to leverage the capabilities of the FPGA fabric, with support for discrete hardware accelerators, dynamically reconfigurable regions, and regions of virtual fabric. We characterise the communication overheads in such a hybrid system to motivate the importance of lean management, before quantifying the context switch overhead of the hypervisor approach. We then compare the resulting idle time for a standard Linux implementation and the proposed hypervisor method, showing two orders of magnitude improved performance with the hypervisor.