A Generalised Approach to the Local Instability of Certain Thin-Walled Struts

1953 ◽  
Vol 4 (3) ◽  
pp. 245-260 ◽  
Author(s):  
A. H. Chilver
Keyword(s):  
Longitudinal Direction ◽  
Local Instability ◽  
Stability Equation ◽  
Cross Sectional ◽  
Small Deflection ◽  
Overall Stability ◽  
Basic Functions ◽  
The Common ◽  
Thin Walled ◽  
Deflection Theory

SummaryThe problem discussed is that of the elastic local instability of a uniformly compressed thin-walled strut composed of a number of flat component plates. The strut is essentially “ open ” in cross-sectional form, while reinforcing flanges are attached to the extreme edges. An overall stability equation, based on the small deflection theory of plate bending, is derived from the conditions which must hold at the common and extreme longitudinal edges of the strut.It is shown that the critical compression stress induces a mode of buckling which involves a whole number of sinusoidal half-waves in the longitudinal direction. Furthermore, the number of half-waves is common to all component plates of the strut. The general’ stability equation—a zero determinant of high order—lends itself to expansion in terms of 4th order minors, which may again be expressed in terms of seven basic functions. A knowledge of these functions is sufficient for the solution of any problem, however complex, within the scope of the general analysis.Application of the basic functions to the solution of three different problems yields results which indicate the need for considerable care in the design of thin-walled struts with reinforcing flanges. In struts of this type a longer wavelength of buckling is possible than is commonly associated with local instability problems.

ASME B31.3 End of Life Considerations: Corrosion, Mechanical Strength, and Small Bore Geometry

2010 ◽  
Author(s):  
Dennis K. Williams
Keyword(s):  
Mechanical Strength ◽  
End Of Life ◽  
Longitudinal Direction ◽  
Careful Examination ◽  
Tabular Form ◽  
Sectional Area ◽  
Cross Sectional ◽  
Section Modulus ◽  
Process Piping ◽  
Thin Walled

This paper discusses the prescribed requirements contained within the ASME B31.3 Process Piping Code that specifically address the considerations of the design corrosion allowance when coincidently taken into account with the mechanical strength requirements of the same. In particular, the most significant effects of the least favorable corrosion allowances in combination with the mechanical strength requirements of ASME B31.3 are prevalent in thin walled, small bore piping of minimal geometric properties associated with the calculation of component stresses in the longitudinal direction. Careful examination of ASME B31.3 paragraph 302.4 reveals that the minimum required thickness of a piping component include allowances for corrosion and when taken in conjunction with paragraph 302.4.1, which requires that when necessary, the wall thickness shall be increased to prevent overstress, damage, or collapse, due to superimposed loads from handling or other causes. The effects of the aforementioned Code requirements are addressed and examples are presented for small bore piping (nps 2″ and below) that lead to a proposed small bore piping criteria for consideration by piping specification engineers. Finally, the results of the evaluation of various combinations of corrosion allowance and mechanical strength requirements in terms of metal cross sectional area and section modulus are presented in tabular form that support the proposed small bore piping criteria.

Buckling of a Thin-Walled Circular Cylindrical Shell Heated Along an Axial Strip

1964 ◽  
Vol 31 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Nicholas J. Hoff ◽  
Chi-Chang Chao ◽  
Wayne A. Madsen
Keyword(s):  
Cylindrical Shell ◽  
Critical Stress ◽  
Circular Cylindrical Shell ◽  
Axial Stress ◽  
Elastic Stability ◽  
Nonuniform Heating ◽  
Small Deflection ◽  
Thin Walled ◽  
Axial Compressive Stress ◽  
Deflection Theory

The elastic stability of a thin-walled circular cylindrical shell is investigated by means of the small-deflection theory when the shell is subjected to such nonuniform heating as causes a uniform axial compressive stress to arise in a band of width 2b while the rest of the shell is free of stress. The critical value of the compressive axial stress is found to be equal to the critical stress of the same circular cylindrical shell when subjected to uniform axial compression provided the band is not extremely narrow. In the latter case the critical stress of the band is higher than that of the uniformly compressed shell.

The Analysis of Stiffness Condition in Rolling Thin-Walled Ring

2012 ◽  
Vol 157-158 ◽  
pp. 702-705
Author(s):  
Zhi Jiang Zuo ◽  
Qin You Han ◽  
Min Min Dai
Keyword(s):  
Rolling Process ◽  
Raw Material ◽  
Ring Rolling ◽  
Theoretical Formula ◽  
Cross Sectional ◽  
Small Deflection ◽  
Section Shape ◽  
Thin Walled ◽  
Coefficient Ring ◽  
Selection Of

The thin-walled ring rolling, a new rolling process, can produce the thin-walled rings that the traditional methods are difficult to process. It has the advantages of simple equipment, low investment and high productive. According to the mechanics analysis of the multiple rollers rolling, it established a mechanical model of small deflection bending compression rod. After solved the mechanics equations, it obtained the thin-walled ring’s rolling stiffness condition. From the theoretical formula, it could find that the increase of friction coefficient, ring radius, roller radius and feed per rotation were disadvantage for the thin-walled ring rolling stiffness condition. However, the increase of the ring cross sectional inertia was advantage for the stiffness condition. The theoretical formula could provide theoretical basis and guidance for the quantity design of roller pairs in rolling machine, design of ring cross section shape and selection of ring raw material.

Side Effects of Chemotherapy and Cancer Treatment in Tertiary Care Teaching Hospital

2016 ◽  
Vol 2 (1) ◽  
pp. 62-78
Author(s):  
. Hemraj ◽  
Raj Kumar ◽  
Sourabh Kosey ◽  
Amit Sharma ◽  
Nalini Negi
Keyword(s):  
Side Effects ◽  
Tertiary Care ◽  
Cross Sectional Study ◽  
Informational Needs ◽  
Cross Sectional ◽  
Clinical Pharmacists ◽  
Medical College ◽  
Related Information ◽  
The Common ◽  
Chemotherapy Patients

To determine the most common physical side effects experienced by local chemotherapy patients. Their perceptions of these side effects and informational needs from clinical pharmacists were also evaluated. This was a single center, observational cross-sectional study conducted at department of General Surgery, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab. A face to face interview was conducted. Information collected included chemotherapy related side effects after last chemotherapy experience, the most worrisome side effects, overlooked by healthcare professionals and the preferred method, amount and source of receiving related information. In this study, hundred patients were enrolled out of them 48 were male and 52 were female. When differential calculations was done, common side effects or adverse effects of chemotherapy in the patients of breast, lung cancer, Ovarian Cancer, Colon cancer, Prostate cancer, Lymphoma Cancer, Cervix cancer where there is much irregular medicine intake 57.4% may be due to common problem of joint pain reported by all the patients under study, with the consecutive problem of nausea and vomiting. The high prevalence of chemotherapy related side effects among local patients is a major concern and findings of their perceptions and informational needs may serve as a valuable guide for clinical pharmacists and physicians to help in side effect management. This study shows the common problems reported by the patients when they are suffering from cancer condition, according to their incidence perceptions as experienced by the patient, this will allow the physician and clinical pharmacist to effectively counsel and manage the common symptoms as reported prior to its occurrence in the patient, so that withdrawal can be checked.

STUDY OF PEDIATRIC INJURIES: PATTERNS AND OUTCOME

2019 ◽  
Vol 3 (8) ◽  
Author(s):  
Yasir. B. Elshambaty
Keyword(s):  
School Level ◽  
Common Mechanism ◽  
Injury Patterns ◽  
Severe Injuries ◽  
Injured Child ◽  
Cross Sectional ◽  
Pediatric Injuries ◽  
Pediatric Injury ◽  
The Common ◽  
Structured Questionnaire

Purpose this study aims to show the patterns and outcome of pediatric injury among those living in Albaha region in Saudi Arabia Methods this is a cross-sectional descriptive household-based study, included children between 0-17 years old both male and female. The data were collected with structured questionnaire between 20 Nov – 20 Dec 2018 and  analyzed with SPSS version 25 Results the total of participants was 257 injured child. 199(77.4%) are male and 58(22.6%) are female. About 44%of them were injured at pre-school level and 56% were traumatized at school age. The least incidence of injury occurred in those less than 2 yrs and higher incidence in those between 3-10 yrs old. The most common mechanism of injury was falling from height. The most affected group age by RTA accidents was 11-17 yrs old. Approximately 83% of the injured children required hospital management. Only one third of the injuries were  associated complications. The most common injured anatomic part was the upper limb and the least affected part was the spine. Only 5% of the injuries were associated with a disability and the common was loss of organ or part of it. Paralysis occurred in less than 1% and head injury resulted in disabilities more than 1%. Conclusion the vast majority of the injuries in our participants are not serious. The severe injuries were associated with RTA-related trauma. Most of injuries due to falling from height are not serious. We recommend not to allow the children to drive cars. Keywords: pediatric injuries; injury patterns; household.

Comparison of Heffner Criteria and Light Criteria in Differentiating Exudative and Transudative Pleural Effusion

2020 ◽  
Vol 22 (3) ◽  
pp. 141-145
Author(s):  
Krishna Chandra Devkota ◽  
S Hamal ◽  
PP Panta
Keyword(s):  
Pleural Effusion ◽  
Cross Sectional Study ◽  
Pleural Space ◽  
Sectional Study ◽  
Inclusion Criteria ◽  
Cross Sectional ◽  
Medical College ◽  
The Common ◽  
The Mean ◽  
Exudative Pleural Effusion

Pleural effusion is present when there is >15ml of fluid is accumulated in the pleural space. It can be divided into two types; exudative and transudative pleural effusion. Tuberculosis and parapneumonic effusion are the common cause of exudative pleural effusion whereas heart failure accounts for most of the cases of transudative pleural effusion. This study was a hospital based cross sectional study performed at Nepal Medical College during the period of January 2016-December 2016. A total of 50 patients who fulfilled the inclusion criteria were enrolled. Pleural effusion was confirmed by clinical examination and radiology. After confirmation of pleural effusion, pleural fluid was aspirated and was analysed for protein, LDH, cholesterol. The Heffner criteria was compared with Light criteria to classify exudative or transudative pleural effusion. Among 50 patients, 30 were male and 20 were female. The mean age of patient was 45.4±21.85 years. The sensitivity and specificity of using Light criteria to detect the two type of pleural effusion was 100% and 90.9%, whereas using Heffner criteria was 94.87%, 100% respectively(P<0.01). There are variety of causes for development of pleural effusion and no one criteria is definite to differentiate between exudative or transudative effusion. In this study Light criteria was more sensitive whereas Heffner criteria was more specific to classify exudative pleural effusion. Hence a combination of criteria might be useful in case where there is difficulty to identify the cause of pleural effusion.

HISTOPATHOLOGY OF THE PIGMENTED TUMORAL-LIKE LESIONS OF THE SKIN AT HUE HOSPITAL OF MEDICINE AND PHARMACY UNIVERSITY

2018 ◽  
Vol 8 (4) ◽  
pp. 65-69
Author(s):  
Mao Nguyen Van ◽  
Dong Tran Nam
Keyword(s):  
Key Words ◽  
Definitive Diagnosis ◽  
The Other ◽  
Cell Tumour ◽  
Cross Sectional ◽  
Skin Tumour ◽  
Clinical Appearance ◽  
The Face ◽  
The Common ◽  
Difficult Cases

Background: Pigmented tumour of the skin is one of the common tumour in human including the benign pigmented tumours (more common) called Nevi tumours and the malignant one called melanoma which was less frequent but the most poor in prognosis. In addition, the others not belonging to these group had the same clinical appearance, so the application of histopathology and immunohistochemistry for the definitive diagnosis was indespensible. Objectives: 1. To describe the macroscopic features of the pigmented tumoral-like lesions; 2. To classify the histopathologic types of the pigmented cell tumours and the other pigmented tumours of the skin. Materials and Method: Cross-sectional research on 55 patients diagnosed as pigmented tumoral lesions by clinician, then all definitively diagnosed by histopathology combining the immunohistochemistry in difficult cases. Results: There was no difference in gender, the disease was discovered most common in adult, especially with the age over 51 years old (58.1%). the most region located was in the face accounting for 60%, following the trunk and limbs (14.6%, 12.8% respectively). All 3 malignant melanomas happened in foot. The most common color of the lesions was black (65.4%), the other ones were rose, grey and blue. Histopathology and immunohisthochemistry showed that the true pigmented cell tumours were 52.6% encompassing benign ones (Nevi tumour) (41.8%), melanoma (5.4%) and lentigo (5.4%). 47.4% was not the true pigmented cell tumour including pigmented basocellular carcinoma (36.4%) and the others less common as histiofibromas, acanthoma and papilloma. Conclusion: the pigmented tumoral-like lesions of the skin could be the true pigmented cell tumours and the others, so the application of the histopathology and the immunohistochemistry after the clinical discovery helps to determine and classify the disease definitely and for the best orientation of treatment as well. Key words: skin tumour, benign pigmented tumour (Nevi), malignant pigmented tumour (melanoma), pigmented basocellular carcinoma

EVALUATING THE RESULTS OF SEPTOPLASTY AND PARTIAL INFERIOR TURBINOPLASTY

2017 ◽  
pp. 46-52
Author(s):  
Thanh Thai Le ◽  
Phuong Nam Tran ◽  
Thi Ngan An Nguyen
Keyword(s):  
Key Words ◽  
Nasal Obstruction ◽  
Inferior Turbinate ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Grade Ii ◽  
The Common

Aims: To study outcomes of septoplasty and partial inferior turbinectomy (PIT) method, expecting leastsurgical equipment, good result, price rationalization. Methods: Prospective, cross-sectional study. Including 40 patients treated by septoplasty and PIT method. Assessment had been made after 3 months post-op. Results: The common symptoms were nasal obstruction (100%), headache (40%). The deformities of nasal septalwere deviation (42.5%), crest (30%). There were 67.5% of patients with severe bilateral hypertrophic inferior turbinate, mostly over grade II, enlargement both soft and bone parts (60%). After 3 months, the nasal obstruction and headache presented good or great results in 90% of patients, 93.7% of patients had straight nasal septaland 90% hadsmall inferior turbinate.VAS: patients’s contentment was 100%. Conclusions: The study showed that septoplasty and partial inferior turbinectomy presented good results with 87.5% after surgery and 90% after 3 months. Key words: septal deformity, hypertrophy inferior turbinate, septoplasty, partial inferior turbinectomy

Decrease in Secondary Neck Vessels in Multiple Sclerosis: A 5-year Longitudinal Magnetic Resonance Angiography Study

2019 ◽  
Vol 16 (3) ◽  
pp. 215-223 ◽  
Author(s):  
Dejan Jakimovski ◽  
Matthew Topolski ◽  
Kana Kimura ◽  
Virja Pandya ◽  
Bianca Weinstock-Guttman ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Longitudinal Change ◽  
Repeated Measure ◽  
Cross Sectional ◽  
False Discovery ◽  
The Common ◽  
Neck Vessels

Background: Studies have previously shown greater arterial and venous extracranial vascular changes in persons with multiple sclerosis (PwMS) when compared to healthy controls (HCs). Objectives: To determine the change in the number and size of secondary neck vessels in PwMS and HCs over a 5-year follow-up period. Methods: Both at baseline and follow-up, 83 PwMS and 25 HCs underwent magnetic resonance angiography (MRA) imaging and analysis. The number and cross-sectional area (CSA) of all secondary neck vessels (excluding the common/internal carotid, vertebral artery, and internal jugular vein) measured at levels from C2-T1 were determined by semi-automated edge detection/ contouring software. The longitudinal change in the number and CSA of the secondary neck vessels from the PwMS and HCs were analyzed by non-parametric Wilcoxon repeated measure. Benjamini-Hochberg procedure adjusted for false discovery rate (FDR). Results: For over 5 years, PwMS demonstrated a consistent longitudinal decrease in both the number of secondary neck vessels (Z-change between -3.3 and -5.4, q=0.001) and their CSA (Zchange between -2.9 and -5.2, q=0.004). On the contrary, the HCs did not demonstrate a significant longitudinal change in secondary neck vessels over the follow-up period. Due to the longitudinal decrease, the PwMS showed a lower number of secondary neck vessels when compared to HCs measured at follow-up (p<0.029, except for C4 with trending p=0.071). The PwMS changes were also corroborated within each MS phenotype. Conclusion: PwMS demonstrate a significant mid-term decrease in the number and the size of the secondary neck vessels. The clinical relevance of these findings and the effect on intracranial blood flow are currently unknown.

Fracture and local instability of thin-walled bodies with notches

1981 ◽  
Vol 17 (8) ◽  
pp. 707-722 ◽  
Author(s):  
A. N. Guz' ◽  
M. Sh. Dyshel' ◽  
G. G. Kuliev ◽  
O. B. Milovanova
Keyword(s):  
Local Instability ◽  
Thin Walled
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