Self-adaptive systems: A survey of current approaches,research challenges and applications

Self-adaptive software is capable of evaluating and changing its own behavior, whenever the evaluation shows that the software is not accomplishing what it was intended to do, or when better functionality or performance may be possible. The topic of system adaptivity has been widely studied since the mid-60s and, over the past decade, several application areas and technologies relating to self-adaptivity have assumed greater importance. In all these initiatives, software has become the common element that introduces self-adaptability. Thus, the investigation of systematic software engineering approaches is necessary, in order to develop self-adaptive systems that may ideally be applied across multiple domains. The main goal of this study is to review recent progress on self-adaptivity from the standpoint of computer sciences and cybernetics, based on the analysis of state-of-the-art approaches reported in the literature. This review provides an over-arching, integrated view of computer science and software engineering foundations. Moreover, various methods and techniques currently applied in the design of self-adaptive systems are analyzed, as well as some European research initiatives and projects. Finally, the main bottlenecks for the effective application of self-adaptive technology, as well as a set of key research issues on this topic, are precisely identified, in order to overcome current constraints on the effective application of self-adaptivity in its emerging areas of application.     

世界军事领域依赖于纺织品

虽说纺织工业不能提供全世界军事领域中所需的坦克、武器或弹药等装备,但毫无疑问的是军事领域也不能没有纺织品。事实上,军事力量一直依赖于纺织品,包括军服、运输附件、睡眠休息装备以及其他数不清的物品。     

Poly(3-hexadecylthiophene)/montmorillonite clay nanocomposites: Influence of preparation and type of clay on their structures

A nanocomposite of poly(3-hexadecylthiophene) (PHDT) with montmorillonite (MMT) was prepared by in situ polymerization (PHDT/MMT) and nanocomposites of PHDT with organomontmorillonite clay (OrgMMT) were prepared by both in situ polymerization (PHDT/OrgMMT) and by the solvent casting method (PHDT/OrgMMT-sc). The nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). PHDT/OrgMMT was also characterized by transmission electron microscopy (TEM). FTIR spectra indicate the presence of the clay in the polymer matrices and show variations on the frequency of the Si–O–Si stretching vibration. The XRD diffractograms indicate that PHDT/MMT and PHDT/OrgMMT-sc are intercalated nanocomposites, while PHDT/OrgMMT is mostly exfoliated, but present also some intercalation, as confirmed by TEM.     

Fusion of remotely sensed data for soil moisture estimation using relevance vector and support vector machines

A data assimilation (DA) methodology that uses two state-of-the-art techniques, relevance vector machines (RVMs) and support vector machines (SVMs), is applied to retrieve surface (0–6 cm) soil moisture content (SMC) and SMC at a depth of 30 cm. RVMs and SVMs are known for their robustness, efficiency and sparseness and provide a statistically sound approach to solve inverse problems and thus to build statistical models. Here, we build a statistical model that produces acceptable estimations of SMC by using inexpensive and readily available data. The study area for this research is the Walnut Creek watershed in Ames, south-central Iowa, USA. The data were obtained from Soil Moisture Experiments 2002 (SMEX02) conducted at Ames, Iowa. The DA methodology combines remotely sensed inputs with field measurements, crop physiological characteristics, soil temperature, soil water-holding capacity and meteorological data to build a two-step model to estimate SMC using both techniques, i.e. RVMs and SVMs. First, the RVM is used to build a model that retrieves surface (0–6 cm) SMC. This information serves as a boundary condition for the second step of this model, which estimates SMC at a depth of 30 cm. An exactly similar routine is followed with an SVM for estimation of surface (0–6 cm) SMC and SMC at a depth of 30 cm. The results from the RVM and SVM models are compared and statistics show that RVMs perform better (root mean square error (RMSE)?= 0.014 m³ m^?3) when compared with SVMs (RMSE?= 0.017 m³ m^?3) with a reduced computational complexity and more suitable real-time implementation. Cross-validation techniques are used to optimize the model. Bootstrapping is used to check over/under-fitting and uncertainty in model estimates. Computations show good agreement with the actual SMC measurements with coefficients of determination (R ²) for RVM equal to 0.92 and for SVM equal to 0.88. Statistics indicate a good model generalization capability with indexes of agreement (IoAs) for RVM equal to 0.97 and for SVM equal to 0.96.     

Erythema migrans-like rash illness at a camp in North Carolina: a new tick-borne disease?

BACKGROUND: Borrelia burgdorferi, the causative agent of Lyme disease, has never been isolated from a patient thought to have acquired Lyme disease in any southeastern state. OBJECTIVE: To investigate 14 cases of an erythema migrans (EM)-like rash illness that occurred during 2 summers at an outdoor camp in central North Carolina in an effort to determine the etiologic, epidemiological, and clinical aspects of this illness. METHODS: Using active surveillance, we identified cases of clinically diagnosed EM in residents and staff of the camp. We collected clinical and demographic information; history of exposure to ticks; acute and convalescent serum antibodies to B. burgdorferi, Rickettsia rickettsii, and Ehrlichia chaffeensis; and cultures for spirochetes from biopsy specimens of skin lesions. Serum samples from a group of residents and staff who did not develop rashes were tested for the same antibodies. We speciated ticks removed from people and collected from vegetation. RESULTS: We identified 14 cases of EM-like rash illness during the 2 summers. Of the 14 case-patients, 10 had associated mild systemic symptoms and 1 had documented fever. All 14 case-patients had removed attached ticks, and 8 remembered having removed a tick from the site where the rash developed a median of 12 days earlier (range, 2-21 days). One tick removed from the site where a rash later developed was identified as Amblyomma americanum, the Lone Star tick; 97% of ticks collected from vegetation and 95% of ticks removed from people were A. americanum. No spirochetes were isolated from skin biopsy specimens. Paired serum samples from 13 case-patients did not show diagnostic antibody responses to B. burgdorferi or other tick-borne pathogens. CONCLUSIONS: This investigation suggests the existence of a new tick-associated rash illness. We suspect that the disease agent is carried by A. americanum ticks. In the southern United States, EM-like rash illness should no longer be considered definitive evidence of early Lyme disease.     

Well differentiated cerebellar tissue within a mature cystic teratoma

OBJECTIVE: Oesophageal self-expanding metal endoprostheses (SEMS, or stents) are recognized as a safe means of palliating dysphagia caused by malignancy. Stent designs that have covered or uncovered walls are now available. The purpose of this study was to compare the outcome of use of these two designs. DESIGN: Thirty consecutive cases were reviewed. All the patients had been referred over a period of 25 months for palliation of dysphagia caused by malignant obstruction. Either a covered or an uncovered stent was placed in each patient. Palliation of dysphagia, 30 day mortality, mean survival time, and the number of endoscopic re-interventions required, were assessed. RESULTS: Uncovered Ultraflex stents were used in 14 patients, and Schneider Wallstents were used in 16 patients. Dysphagia improved by one grade or more in 69% of patients. The 30 day mortality was 27%, with an overall mean survival time of 99 days. There was no significant difference between the two groups for these three parameters. Ten patients needed a total of 28 repeat endoscopic procedures to maintain stent patency, with overall rates for each group of 1.64 procedures per patient, for uncovered stents, compared with 0.31 for covered stents (significant at the P < 0.05 level). The number of repeat procedures increased with survival time. CONCLUSION: The use of covered self-expanding metal oesophageal endoprostheses is associated with a significant reduction in the need for endoscopic reintervention after stent placement.     

Differential protein oxidation in Duchenne and Becker muscular dystrophy

BACKGROUND: The fifth edition of the TNM classification contains a number of changes concerning head and neck tumors. The division of Stage IV tumors into three subcategories marks a significant expansion of the stage grouping procedure. METHODS: In a retrospective study, the clinical courses of 3247 patients with carcinoma of the oral cavity, the oro- and hypopharynx, the larynx, the salivary glands, and the maxillary sinus were comparatively evaluated according to the fourth and fifth editions of the TNM classification agreed upon by the International Union Against Cancer and the American Joint Committee on Cancer. The particular aim of this study was to test the prognostic relevance of the subdivision of Stage IV, especially for mucosal carcinoma. RESULTS: In classifying the primary tumor, the most extensive changes were noted for supraglottic and salivary gland tumors. On the basis of the fourth edition of the TNM classification, the following recurrence free 5-year survival rates for 3033 cases of mucosal cancer were calculated: Stage I, 91.0%; Stage II, 78.6%; Stage III, 61.4%; Stage IV, 31.0%. The calculations based on the fifth edition yielded the following: Stage I, 91.0%; Stage II, 77.2%; Stage III, 61.2%; Stage IVA, 32.4%; Stage IVB, 25.3%; Stage IVC, 3.6%. CONCLUSIONS: The adequacy of the revised stage classification in establishing a prognostic hierarchy was confirmed. However, a significant prognostic distinction between N2 metastasis (Stage IVA) and N3 metastasis (Stage IVB) could not be found.     

Characterization and Physical Explanation of Energetic Particles on Planck HFI Instrument

The Planck High Frequency Instrument (HFI) has been surveying the sky continuously from the second Lagrangian point (L2) between August 2009 and January 2012. It operates with 52 high impedance bolometers cooled at 100 mK in a range of frequency between 100 GHz and 1 THz with unprecedented sensitivity, but strong coupling with cosmic radiation. At L2, the particle flux is about 5 \(\hbox {cm}^{-2}\,\hbox {s}^{-1}\) and is dominated by protons incident on the spacecraft. Protons with an energy above 40 MeV can penetrate the focal plane unit box causing two different effects: glitches in the raw data from direct interaction of cosmic rays with detectors (producing a data loss of about 15 % at the end of the mission) and thermal drifts in the bolometer plate at 100 mK adding non-Gaussian noise at frequencies below 0.1 Hz. The HFI consortium has made strong efforts in order to correct for this effect on the time ordered data and final Planck maps. This work intends to give a view of the physical explanation of the glitches observed in the HFI instrument in-flight. To reach this goal, we performed several ground-based experiments using protons and \(\alpha \) particles to test the impact of particles on the HFI spare bolometers with a better control of the environmental conditions with respect to the in-flight data. We have shown that the dominant part of glitches observed in the data comes from the impact of cosmic rays in the silicon die frame supporting the micro-machined bolometric detectors propagating energy mainly by ballistic phonons and by thermal diffusion. The implications of these results for future satellite missions will be discussed.