压力容器用封头制造质量控制和专业化生产发展方向

中国法规首次对压力容器等特种设备用封头实施制造资格许可和强制的监督检验制度。本文根据法规标准的规定,对压力容器封头制造质量控制和专业化生产发展方向的要求作一系统的综述,以提高压力容器产品的整体质量,确保特种设备安全万无一失。     

MODELING SIMULATION AND CONTROL OF THE WOOD DRYING PROCESS Part 3. Programming and Computer Solutions

Abstract

In this paper, the programming and computer subroutines of wood drying process (WDP) are studied. This WDP is represented by the set of non-linear partial differential equations which are decomposed into fast and slow subsystems. Moreover, a few procedures have been used to estimate piecewise linear parameters and to reconstruct the real parameter distributions along the drying kiln. Several aspects including estimating stepsize, tuning sensitivity of the operating functions, and general solutions of the internal model (M) are discussed and illustrated     

Choroidal melanoma: a review and case report

BACKGROUND: Choroidal melanoma is the most common primary intraocular malignancy in adults. The ongoing Collaborative Ocular Melanoma Study (COMS) was designed to provide specific answers for the management of medium and large choroidal melanomas. The present consensus among authorities is that small (< 3 mm thick) suspected choroidal melanomas can be conservatively managed with periodic observation for evidence of growth. CASE REPORT: Dilated fundus examination of a 68-year-old man revealed a pigmented uveal lesion straddling the ora serrata inferiorly at 5:30 in the right eye. It measured 5 mm in diameter with transillumination and 2.89 mm in thickness with B-scan ultrasonography. Questioning a small choroidal melanoma the patient was referred to an ocular oncologist, who confirmed the lesion was suspicious for choroidal melanoma. CONCLUSION: Although there are clinical signs that suggest lesion growth, true growth must be recorded with serial photographs, ultrasound, and transillumination. Active therapy should usually begin once lesion growth is documented.     

Effect of 2 types of diet changes on dietary habits, body weight and cholesterol levels in high risk cardiovascular patients

Several non-pharmacological interventions such as weight reduction in obese subjects or diet alteration in subjects having hypercholesterolemia have been shown to be effective in therapeutic trials. Our aim was to test the value of two different ways of teaching patients about their diet. From March 1, 1993, to May 30, 1994, 300 consecutive patients seen in a one-day care hospital were randomised into two groups. The 2 inclusion criteria were: 1) body mass index > 27 kg/m2 in men and > to 25 kg/m2 in women and/or 2) presence of a hypercholesterolemia defined by a total cholesterol > 6.5 mmol/l. Patients in the first group (C) were educated in a 20 to 50 minutes consultation tailored to their needs. Patients in the second group (CC) were given in addition a one-hour course about diet. The goal of the diet was to loss at least 3 kg of body weight and/or to have a cholesterol value below 6.5 mmol/l without treatment. All Patients were followed-up by the same 3 dietician nurses. An out-patient visit was planned at 3 months, and a recall letter was sent to the patients who missed their appointments. Among the 300 patients, 169 (55%) were seen at the 3-month outpatient visit. This proportion did not differ between the 2 groups. Knowledge on diet was assessed by the same 33-item self-administered questionnaire. At baseline scores were comparable between groups (16 vs 17). Scores improved more in the CC than in the C group both at the end of the teaching question (27 vs 23 in the CC and C group respectively, p < 0.001), and at 3 months (25 vs 23 in the CC and C group respectively; p < 0.001). Total cholesterol decreased below 6.5 mmol/l in 28% of the patients with dyslipidemia and a weight loss > 3 kg was observed in 32% of the obese subjects, but improvement did not differ between the 2 groups. We conclude that a specific one-hour course on diet is able to improve knowledge of patients more than a consultation alone, but that better knowledge did not result in improved alteration of risk factors at 3 months.     

Pseudopotentials and Loading Surfaces for an Endochronic Plasticity Theory with Isotropic Damage

The endochronic theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this theory and the classical theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the endochronic plasticity theory was modified in order to introduce the effect of damage. In the present paper, a basic endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an endochronic model of plasticity with damage is investigated and an insightful comparison with classical models is made possible. A damage pseudopotential definition allowing a very general damage evolution is given.     

Comparison of the cumulative probability of pregnancy after in vitro fertilization-embryo transfer by infertility factor and age

OBJECTIVE: To compare the cumulative probability of pregnancy after multiple IVF cycles by age and cause of infertility. DESIGN: A prospective study was done in which patients were followed from the time they registered for their first IVF cycle until they achieved a clinical pregnancy, withdrew from treatment, or study was terminated. PATIENTS, SETTING, TREATMENTS: Infertile women undergoing IVF-ET at the Cooper Institute for In Vitro Fertilization were enrolled in this study if the luteal phase leuprolide acetate (LA) and hMG controlled ovarian hyperstimulation (COH) regimen was used. MAIN OUTCOME MEASURES: Clinical pregnancy, as determined by a positive beta-hCG level and ultrasonographic confirmation of a gestational sac, and delivery rates based on number of women with live births were compared by infertility factor and age. RESULTS: The 3-month cumulative probability of pregnancy based on life table analysis was 33% in women with tubal factor who were < or = 35 years of age, 25% in women with tubal factor who were > 35 years of age, 30% for women with multiple factors who were < or = 35 years of age, and 14% for women with multiple factors who were > 35 years of age. The rate for the older women with multiple factors was significantly lower than that for the other groups. The delivery rates were lower for the women with multiple factors than for women under 35 with tubal factor only. CONCLUSIONS: There is a significant effect of age and infertility factor on pregnancy and delivery rates. Physicians should consider these factors in evaluating their patients' prospects for success in IVF-ET.     

VSAT-enhanced ISDN: architectures and implementation

The authors discuss the applications of very small aperture terminals (VSATs) to the ISDN. Typical VSAT network architectures include point-to-point interactive, point-to-multipoint broadcast, and interactive star configurations. VSATs and satellite communications have found new applications for integrated network solutions yielding hybrid network architectures that mix terrestrial and satellite segments. These issues and their implications are examined in the context of ISDN. Six hybrid network configurations are described to address various applications. A proof of concept implementation utilizing a hybrid terrestrial/satellite ISDN network was performed. The demonstration showed the feasibility of using hybrid networks as a backup for terrestrial communications as well as for service extension via satellite. The architecture and implementation of this configuration are described     

Intraoral repair of chipped or fractured veneered zirconia crowns and fixed dental prosthesis: clinical guidelines based on literature review

This article aimed to review the susceptibility to chipping, influencing factors, current protocols for intraoral repair and provide the clinicians with guidelines for repairing. Peer-reviewed literature in English published between 01/01/2000 and 30/06/2017 was electronically searched using PubMed and Google Scholar, followed by manual search of the scientific literature. Multiple key words and their combinations (‘Zirconium’, ‘Zirconia’, ‘Intraoral’, ‘Repair’, ‘Chipping’, ‘Fracture’, ‘Bonding’, and ‘Surface treatment’) and different search strategies were employed for sample selection. The initial search resulted in 189 articles, of which 98 were included in this review. The chipping rates of veneered zirconia-based restorations have been reported range between 0 and 44%. Researchers and clinicians were in favor of the intraoral repair of chipped veneered zirconia-based restorations. While various intraoral repair protocols were available based on the severity of chipping, decisions about intraoral repair were based on the clinical situation, availability/accessibility of repair kits, survival/success rate of repairing, and patient concerns. Intraoral repair seems to be a promising option to correct moderate size of chipping, and its success largely depends on the surface treatment methods used for the fractured surfaces. Hydrofluoric acid etching of the veneering porcelain followed by silanization and air-abrasion of the zirconia framework and then MDP priming have been recommended to create durable bonds. This review suggests that intraoral repair of chipped zirconia-based restorations offers a satisfying option for the patient when restoration replacement is not an option. Treatments for the fracture surface are the most important factors influencing the longevity of repaired zirconia-based restorations.     

Primary hyperparathyroidism secondary to parathyroid carcinoma: report of a case

Distinguishing parathyroid carcinoma from benign hyperparathyroidism is often difficult. Clinical features most commonly associated with parathyroid carcinoma, such as palpable cervical mass, markedly higher serum calcium, high parathyroid hormone immunoassay, and evidence of bone disease may not be present. Therefore, intraoperative recognition is essential. We report a case in which the presenting symptoms, physical examination, and laboratory analysis were consistent with benign disease. During surgery, the finding of an enlarged firm gland with surrounding inflammatory reaction altered the approach to include the possibility of parathyroid carcinoma. The gland and surrounding tissue were removed, and pathologic examination led to the diagnosis of carcinoma. At 18-month follow-up, the patient was free from recurrence. Any parathyroid gland with a gray appearance, firm texture, and surrounding inflammatory reaction should be treated as carcinoma. Initial intraoperative recognition offers the best chance for cure, since local recurrences are rarely curable.