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161.
In variable humidity conditions, wood absorbs or desorbs moisture from the air. Unless the change in humidity is very slow, this will develop moisture gradients in the wood sections. These gradients will develop stresses due to constrained swelling or shrinkage strains. These stresses are named moisture-induced stresses. The present paper investigates the main parameters affecting such moisture-induced stresses, including the type of climate, the size of the timber cross-section, and the type of protective coating. A first attempt to identify moisture-induced stresses in different European climatic regions was made. For each climatic region, relative humidity and temperature histories were identified, and characteristic and mean values of yearly and daily variations were calculated. Using a finite element model implemented in Abaqus, the moisture content and stress distribution were computed on different timber cross-sections exposed to the climatic regions and protected with different types of coating. A Fickian moisture transfer model was used to compute the moisture distribution, and a mechanical model for time-dependent behaviour of wood was implemented to calculate the corresponding stress distribution. The variation of moisture was found to result in stresses of magnitudes that would probably cause cracking of wood in the perimeter of any uncoated cross-section size. The use of a protective coating, however, reduced considerably the moisture-induced stresses, and can be regarded as an effective protective measure to avoid cracking due to humidity variations. Considering European climates, Northern climates were found to result in higher surface tensile stresses than Southern climates. 相似文献
162.
Haydar Cukurtepe Massimo Tornatore Aysegul Yayimli Biswanath Mukherjee 《Photonic Network Communications》2014,27(3):154-166
In mixed-line-rate (MLR) networks, different line rates on different wavelengths can coexist on the same fiber. MLR architectures can be built over transparent optical networks, where the transmitted signals remain in the optical domain along the entire path. Along the transparent optical path, a signal experiences various physical layer impairments (PLIs), and its quality degrades as it travels through each optical component. One of the major factors that affect the transmission quality is the launch power of the optical signal. The power must be large enough to ensure noise resiliency at the receiver, but it must be below the limit where fiber nonlinearities distort the signal. Moreover, high launch power is disruptive not only for the actual lightpath itself but also for neighboring lightpaths, and this effect is particularly critical in MLR networks since advanced modulation techniques used for high line rates are highly susceptible to PLIs. In this study, we investigate the problem of determining the appropriate launch power for provisioning of dynamic connection requests in MLR networks. By setting the appropriate launch power for each connection, we aim to maximize the number of established connections. We propose two different heuristics to determine the appropriate launch power of a lightpath. Worst-case best-case average (WBA) is based on optical reach of signal in a transparent optical network. In impairment-aware launch power determination (I-ALPD), current state of the network and impairments are evaluated to determine the launch power. The proposed approaches are practical and can adapt to the needs of network operators. Simulation results show that the performances of the proposed approaches show better results than the existing schemes in terms of blocking probability and bandwidth blocking ratio. 相似文献
163.
S. Sedef Savas Ferhat Dikbiyik M. Farhan Habib Massimo Tornatore Biswanath Mukherjee 《Photonic Network Communications》2014,28(2):123-134
Cloud services delivered by high-capacity optical datacenter networks are subject to disasters which may cause large-area failures, leading to huge data loss. Survivable service provisioning is crucial to minimize the effects of network/datacenter failures and maintain critical services in case of a disaster. We propose a novel disaster-aware service-provisioning scheme that multiplexes service over multiple paths destined to multiple servers/datacenters with manycasting. Our scheme maintains some bandwidth (i.e., degraded service) after a disaster failure vs. no service at all. We formulate this problem into a mathematical model which turns out to be an Integer Linear Program (ILP), and we provide heuristic optimization approaches as ILP is intractable for large problem instances. Numerical examples show that exploiting manycasting by intelligently selecting destinations in a risk-aware manner for service provisioning offers high level of survivability against link and node failures that may be caused by disasters and post-disaster failures at no extra cost compared to the other survivable schemes. 相似文献
164.
Sabrina Caporali Biagio Didona Mauro Paradisi Alessandro Mauriello Elena Campione Mattia Falconi Federico Iacovelli Marilena Minieri Massimo Pieri Sergio Bernardini Alessandro Terrinoni 《International journal of molecular sciences》2021,22(13)
Palmoplantar keratodermas (PPKs) are characterized by thickness of stratum corneum and epidermal hyperkeratosis localized in palms and soles. PPKs can be epidermolytic (EPPK) or non epidermolytic (NEPPK). Specific mutations of keratin 16 (K16) and keratin 1 (K1) have been associated to EPPK, and NEPPK. Cases of mosaicism in PPKs due to somatic keratin mutations have also been described in scientific literature. We evaluated a patient presenting hyperkeratosis localized monolaterally in the right palmar area, characterized by linear yellowish hyperkeratotic lesions following the Blaschko lines. No other relatives of the patient showed any dermatological disease. Light and confocal histological analysis confirmed the presence of epidermolityic hyperkeratosis. Genetic analysis performed demonstrates the heterozygous deletion :r.274_472del for a total of 198 nucleotides, in KRT1 cDNA obtained by a palmar lesional skin biopsy, corresponding to the protein mutation NM_006121.4:p.Gly71_Gly137del. DNA extracted from peripheral blood lymphocytes did not display the presence of the mutation. These results suggest a somatic mutation causing an alteration in K1 N-terminal variable domain (V1). The deleted sequence involves the ISIS subdomain, containing a lysine residue already described as fundamental for epidermal transglutaminases in the crosslinking of IF cytoskeleton. Moreover, a computational analysis of the wild-type and V1-mutated K1/K10 keratin dimers, suggests an unusual interaction between these keratin filaments. The mutation taster in silico analysis also returned a high probability for a deleterious mutation. These data demonstrate once again the importance of the head domain (V1) of K1 in the formation of a functional keratinocyte cytoskeleton. Moreover, this is a further demonstration of the presence of somatic mutations arising in later stages of the embryogenesis, generating a mosaic phenotype. NP_006112.3相似文献
165.
166.
G Massimo Claar S Monaco C Del Veccho Blanco L Capurso M Fusillo B Annibale 《Canadian Metallurgical Quarterly》1998,12(5):463-468
Amyloid deposition in skeletal muscle is a well-recognized but rare occurrence. Sixteen such cases seen in a 17-year period (1979 to 1996) out of a total of 3,937 muscle biopsy specimens (0.004%) form this study group. Either Congo red or sulfated alcian blue stains were routinely performed in each biopsy to screen for amyloid. Patients in this study (eight men, eight women) ranged in age from 42 to 90 years (mean, 61 years) at initial presentation. The most common symptoms at presentation included weakness/fatigue (n = 10), autonomic symptoms (n = 8), and weight loss/decreased appetite (n = 7). Five patients had a concomitant malignancy (myeloma, n = 3; malignant carcinoid tumor, n = 1; melanoma, n = 1). Two patients had known hereditary forms of amyloidosis. Five patients had amyloid diagnosed on another organ biopsy (excluding peripheral nerve). Histologically, amyloid was deposited in the interstitium or perivascular region in 14 muscles and endomysial region in seven muscles. All cases were confirmed with Congo red staining (apple green birefringence) or by electron microscopic identification of fibrillary amyloid material. Scattered angular atrophic esterase-positive muscle myofibers indicative of acute denervation atrophy were seen in 14 muscles. Eight muscles showed small group atrophy, and seven showed myofiber type grouping. Scattered regenerating muscle fibers were seen in nine cases, degenerating myofibers in six, and foci of chronic endomysial and perivascular inflammation in two. Four muscles showed type II muscle fiber atrophy. A concomitant sural nerve biopsy specimen was evaluated in seven patients; all seven contained amyloid, confirmed either by Congo red staining or electron microscopic examination. In two nerves, there was a mild loss of myelinated axons; four had a moderate loss, and one, severe loss. Six of seven nerves showed predominantly axonopathic changes. In conclusion, (1) the prevalence rate of amyloid myopathy in muscle biopsy specimens was low (in this series, 0.004%); (2) only a minority of patients had multiple myeloma, and most presented with muscle weakness/fatigue or autonomic symptoms; (3) most of the muscles showed neurogenic features histologically; (4) all concomitant sural nerve biopsy specimens contained amyloid, and most showed a predominance of axonopathic changes. 相似文献
167.
Often hard real-time systems require results that are produced on time despite the occurrence of processor failures. This paper considers a distributed system where tasks are periodic and each task occurs in multiple copies which are periodically synchronized in order to handle failures. The problem of preemptively scheduling a set of such tasks is discussed where every occurrence of a task has to be completely executed before the next occurrence of the same task. First, a static scheduling algorithm is proposed which uses periodic checkpoints to tolerate processor failures. Then, the performance of the algorithm is substancially improved employing a mixed strategy which constructs a schedule where high frequency tasks are duplicated, and low frequency tasks are periodically checkpointed. The performance of the solution proposed is evaluated in terms of the minimum achievable processor utilization due to the useful computation of the tasks. Moreover, analytical and simulation studies are used to reveal interesting trade-offs associated with the scheduling algorithm. In particular, if high frequency tasks are less than 70 percent of the total number of tasks then the mixed strategy yields a higher processor utilization than the task duplication scheme. 相似文献
168.
The article presents the inverse dynamics model of a novel translating parallel machine and proposes the structure of a force controller for the execution of tasks characterised by interaction with the environment. The task space model of machine’s dynamics is obtained in an efficient and compact form by means of the principle of virtual work. A virtual prototyping environment has been set up to test by computer simulation the potential of such kinematic architecture: the resulting dynamics is rather poor, mainly due to the high moving masses, but it is shown that hybrid position/force control schemes should be able to provide good performances, including the case of rather difficult operations, such as the peg-in-hole assembly. 相似文献
169.
Simone Orcioni Giorgio Biagetti Massimo Conti 《Analog Integrated Circuits and Signal Processing》2004,38(2-3):215-231
A mixed analog-digital fuzzy logic inference processor chip, designed in a 0.35-μm CMOS technology, is presented. The analog fuzzy engine is based on a novel current-mode CMOS circuit used for the implementation of fuzzy partition membership functions. The architecture consists of a 3 inputs—1 output analog fuzzy engine, internal digital registers to store the parameters of the fuzzy controller, and a digital subsystem that allows the programmability of the fuzzy controller via an I 2 C interface. The architecture, circuits, and some Cadence Spectre simulations are presented. 相似文献
170.
Massimo La Deda Mauro Ghedini Iolinda Aiello Irene De Franco 《Inorganic chemistry communications》2004,7(12):1273-1276
This communication reports the synthesis of polymetallic species formed by a zinc-tetraphenolporphyrinate core (ZnTPP(OH)4, 1) and peripheral gallium-quinaldinate fragments. The photophysical analysis of 1 and of the model compound , R, shows an appreciable overlap between the absorption spectra of 1 and the emission spectra of R, suggesting the presence of a donor–acceptor energy-transfer process. Contrarily, the obtained results indicated that energy transfer does not occur, hence these polymetallic complexes work as double emitting species, for which the colour of luminescence depends on the excitation energy. 相似文献