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41.
    
A systematic algorithm for determining the output frequencies generated by a nonlinear system subject to a general multi-tone input, including a bias input, is presented. The algorithm is very efficient, and circumvents many of the difficulties of ‘duplicate frequencies’ that are often generated using previous methods. The inclusion of the dc bias component in the analysis is also important because of the significant effect that non-zero mean inputs can have on nonlinear system response. The algorithm is straightforward to implement on a computer, and the results are illustrated by means of an example.  相似文献   
42.
    
The behaviour of a nonlinear system can be profoundly affected by the presence of a constant or dc term in the system governing equation. These changes are reflected in the nonlinear frequency response characteristics of the system which provide a powerful insight into the system's dynamics. In this article, a new and efficient algorithm is presented for computing the higher order Volterra frequency response functions from nonlinear time-domain models that may contain a constant term. A comparison with previous methods is included to demonstrate the significant gains in computational efficiency that are achieved using the new method. The algorithm is applicable to systems modelled by nonlinear differential, or difference, equations and is easily automated. Several examples are used to illustrate the method, and to highlight the importance of dc terms in nonlinear system analysis.  相似文献   
43.
    
Tissue engineering approaches, with the goals of replacing or recovering damaged or diseased tissues, or of reconstituting tissues in vitro for disease modeling and drug development, have the potential to make significant contributions to medicine. Advances in stem cell biology, biomaterial synthesis and characterization, and microscale technologies have made engineered tissues a reality. However, the classic tools used to build tissues in the lab do not allow for complete control of cell behaviors. More recently, synthetic biology principles have developed robust and versatile approaches to program cells with artificial genetic circuits, where cell behavior and function can be manipulated. At the interface between synthetic biology and tissue engineering, there is space for a new area of investigation where material engineering and cellular engineering complement and sustain each other. In this progress report, synthetic biology principles and how they have been used to engineer cells with potential to dictate cell behavior and function in tissue constructs of the future are briefly described. It is believed that this research area still needs further exploration to fully exploit synthetic biology to make smart and functional cellular constructs for therapeutic and in vitro applications.  相似文献   
44.
    
The extraction of interstitial fluid (ISF) from skin using microneedles (MNs) has attracted growing interest in recent years due to its potential for minimally invasive diagnostics and biosensors. ISF collection by absorption into a hydrogel MN patch is a promising way that requires the materials to have outstanding swelling ability. Here, a gelatin methacryloyl (GelMA) patch is developed with an 11 × 11 array of MNs for minimally invasive sampling of ISF. The properties of the patch can be tuned by altering the concentration of the GelMA prepolymer and the crosslinking time; patches are created with swelling ratios between 293% and 423% and compressive moduli between 3.34 MPa and 7.23 MPa. The optimized GelMA MN patch demonstrates efficient extraction of ISF. Furthermore, it efficiently and quantitatively detects glucose and vancomycin in ISF in an in vivo study. This minimally invasive approach of extracting ISF with a GelMA MN patch has the potential to complement blood sampling for the monitoring of target molecules from patients.  相似文献   
45.
Pneumonia is the most common serious complication of varicella infection in adults. A variety of thrombotic complications including purpura fulminans and disseminated intravascular coagulation have been reported in children with varicella but not in adults. Two men with varicella pneumonia who had profound lower extremity ischemia caused by thrombosis of the profunda femoris and tibial arteries are reported. Both patients had free protein S deficiency and vascular thrombosis in association with varicella pneumonia without overt evidence of disseminated intravascular coagulation or purpura fulminans. Antiphospholipid immunoglobulin G and immunoglobulin M antibodies were present in one, whereas the other had evidence of the lupus anticoagulant. The proposed pathogenesis and management options including intraarterial thrombolytic therapy with urokinase and the need for long-term anticoagulation are discussed.  相似文献   
46.
An electromagnetic (EM) sensor, capable of detecting the formation of ferromagnetic ferrite from paramagnetic austenite below the Curie temperature, has been developed and assessed. In this article, results obtained using an a.c. EM sensor for a medium (0.45 wt pct)-carbon steel slow cooled through its transformation-temperature range are presented. It was found that the EM sensor can successfully detect the formation of ferrite below the Curie temperature, but that the transimpedance values can be significantly affected by the formation of a decarburized ferrite ring around the samples. It was also found that the transimpedance value is monotonically (nonlinearly) related to the ferrite volume fraction and depends on the morphology/distribution of the ferromagnetic phase and, hence, is influenced by the prior-austenite grain size. Results from finite-element (FE) simulations designed to enable prediction of the transimpedance from the microstructure are also presented, showing that two-dimensional (2-D) FE simulations can be successfully used to model the experimental trends observed. The combination of modeling and measurement has shown that EM sensors can be used to indirectly monitor the ferrite transformation (below the Curie temperature), thus providing a measure of ferrite volume fraction and also a means of identifying the ferrite distribution in the microstructure.  相似文献   
47.
This paper presents the measurement of decarburization of steel rods with an electromagnetic sensor using an analytical model both in online and offline scenarios. Loss of carbon (decarburization) at the steel surface can have a significantly detrimental effect on mechanical properties of products, since hardness, fatigue, strength and wear properties are strongly dependent on carbon content. Currently, measurement of decarburization is by destructive methods, such as metallographic observation or hardness tests on a sample cross-section after processing. A non-destructive EM method is proposed in this paper. An analytical solution for the inductance of a circular air-cored coil encircling a steel rod is deduced and further a simplified model is obtained which shows that for both online and offline cases, the thickness of the decarburisation layer is proportional to the inductance difference with and without decarburisation. Using this simplified model, decarburisation thickness can be obtained. The results have been verified by both finite element models and metallographic observations.  相似文献   
48.
State in Haskell     
Some algorithms make critical internal use of updatable state, even though their external specification is purely functional. Based on earlier work on monads, we present a way of securely encapsulating stateful computations that manipulate multiple, named, mutable objects, in the context of a non-strict, purely-functional language. The security of the encapsulation is assured by the type system, using parametricity. The same framework is also used to handle input/output operations (state changes on the external world) and calls to C.  相似文献   
49.
In Experiment I a Latin square design was used to study the utilization of urea nitrogen adsorbed on flaked soybean hulls in normal rations of high producing dairy cows. Concentrates containing urea, urea with supplemental minerals, or soybean meal as the protein supplement were fed with corn silage and alfalfa in a total ration of approximately 17% crude protein. Both urea concentrates contained 2.7% urea. Animals fed urea and soybean had similar milk yields (28.7 and 27.9 kg/day), milk protein, and digestible dry matter intakes. Urea with mineral produced lower milk yield (25.3 kg/day), milk protein, and dry matter intakes, probably because of excessive mineral content. Urea nitrogen of plasma was similar for all three diets. Essential amino acids of plasma were lower for urea than for soybean while for urea mineral the essential amino acids were midway between the other two. In Experiment 2 a switchback design was used to compare the urea-soybean hull concentrate diet of Experiment 1 (17% crude protein) to a negative control diet consisting of its basal components without urea adjusted to 12% protein with wheat bran. Milk yield was 1.2 kg/day higher when the urea diet was fed. Perhaps due to improved urea distribution in the rumen, flaked soybean hulls with urea were effective in maintaining the feed intake necessary for high milk production.  相似文献   
50.
E-Health systems, through their use of Internet and wireless technologies, offer the possibility of near real-time data integration to support the delivery and management of health care. In practice, the wide range of choice in technologies, vendors, protocols, formats, and information representations can make even simple exchanges of information between systems problematic. Much of the focus on healthcare interoperability has been on resolving interoperability issues of system to system information exchanges. But issues around people to people interactions and people to system interactions are just as important to address from an interoperability point of view. In this paper, we identify interoperability deficiencies in collaborative care delivery and develop a methodology in two parts. In the first part, an ontology is developed to represent collaborative care delivery. In the second part, the ontology is used to design an architecture for interoperable clinical information system design. We then use a case study in palliative care to provide a proof of concept of the methodology. The case study provides an inventory of the interoperability requirements for palliative care and a perspective on the design and implementation of a people oriented clinical information system that supports collaborative health care delivery in palliative care.  相似文献   
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