A Combinatory Design Methodology Dedicated to the Ball and Roller Screw Drives for Optimum Design

Author(s):  
Pierre Dupont

Machine-tools, packaging units, lifting systems and also other heavy duty devices (f.e. used in steel casting technologies) employ advantageously screw drives (balls, re-circulating rollers, and planetary roller drives) as mechanical command elements (f.e. directly coupled to servo drives), especially for their high efficiencies (∼87 .. 98%) and “output force to input torque ratio”. After a short review of the most important checks (for Static and Endurance Strength, Life, Shocks resistance and also some Miscellaneous Effects due f.e. to Critical Speeds and Stress Concentrators) it will be described briefly a combinatory design methodology or “heuristics” which takes into account as the technical viability and reliability as well as the economical feasibility of the whole system line (included end bearings and transmission) leading to an “overall safety ratio matrix” and/or to “viability and reliability graphs” helping in such a way the designer to reach an “optimum design” by an overall helicopter view of his/her design(s). In terms of optimization techniques, this user friendly combinatory design methodology could be placed in the field of the “heuristic” ones. An industrial case study will illustrate that presentation. This presentation is also a continuation of the one given for the MS&T’09 occurring in PITTSBURGH, USA during the “Charles R. MORIN Memorial Symposium on Failure Analysis & Prevention” for the ASM International.

2020 ◽  
Vol 36 (8) ◽  
pp. 29-31

Purpose Reviews the latest management developments across the globe and pinpoints practical implications from cutting-edge research and case studies. Design/methodology/approach This briefing is prepared by an independent writer who adds their own impartial comments and places the articles in context. Findings The problem with developing a reputation of being something of an oracle in the business world is that all of a sudden, everyone expects you to pull off the trick of interpreting the future on a daily basis. Like a freak show circus act or one-hit wonder pop singer, people expect you to perform when they see you, and they expect you to perform the thing that made you famous, even if it is the one thing in the world you don’t want to do. And when you fail to deliver on these heightened expectations, you are dismissed as a one trick pony, however good that trick is in the first place. Originality/value The briefing saves busy executives and researchers hours of reading time by selecting only the very best, most pertinent information and presenting it in a condensed and easy-to-digest format.


2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Kamlesh M. Chikhaliya ◽  
Bhaveshkumar P. Patel

Flanged and flued type expansion joint (thick wall expansion bellow) used as an integral part of many shell and tube heat exchanger where process conditions produce differential expansion between shell and tubes. It provides flexibility for thermal expansion and also functions as a pressure retaining part. Design of expansion joints is usually based on trial and error method in which initial geometry must be assumed, and accordingly maximum stresses and spring rate are be calculated. Inadequate selection of geometry leads to higher tubesheet and bellow thickness, which increases cost of equipment. This paper presents standardization and optimum design approach of flange and flued expansion bellow fulfilling ASME VIII-1 and TEMA standard requirement. Methodology to define expansion bellow geometry is developed, and geometry dimensions are tabulated for expansion bellow diameter from 300 to 2000 mm and thickness from 6 to 30 mm. Each defined geometry is analyzed using finite element method, and maximum von Mises stresses are calculated for bellow axial displacement from 0.5 to 1.5 mm and internal pressure from 0.1 to 6.5 MPa. Spring rate is also calculated for each defined geometry for consideration in tubesheet calculation. Accordingly, optimum design methodology is developed, tested, and compared with existing design. Results depicted that proposed standardization approach and design methodology will optimize expansion bellow and tubesheet thickness and will also save considerable time in finalization of heat exchanger design.


2008 ◽  
Vol 51 (spe) ◽  
pp. 83-89
Author(s):  
Anke Bergmann ◽  
Juliana Miranda Dutra de Resende ◽  
Sebastião David Santos-Filho ◽  
Marcelo Adeodato Bello ◽  
Juliana Flavia de Oliveira ◽  
...  

Breast cancer is still associated with high mortality rates and one of the most important factors governing long survival is accurate and early diagnosis. In underdeveloped countries, this disease frequently is only detected in advanced stages; however, through mammography, many women have been diagnosed at early stages. In this context, the sentinel lymph node (SLN) technique is associated with less postoperative morbidity compared to axillary lymphadenectomy. Lymphoscintigraphy has emerged as a method for the evaluation of lymphatic drainage chains in various tumours, being both accurate and non invasive. The aim of this work is to present the main aspects which cause controversy about SLN and lymphoscintigraphy and the impact that these procedures have had on lymphedema after surgical treatment for breast cancer. A short review including papers in English, Spanish and Portuguese, available on Lilacs and Medline database, published between January, 2000 and July, 2008 was performed. The key words breast cancer, lymphoscintigraphy, SLN biopsy, lymphedema were used. Various studies have aimed to compare the incidence and prevalence of lymphedema according to the technique used; however, the population subjected to SLN is different from the one with indication for axillary lymphadenectomy regarding staging. Moreover, little is known about long term morbidity since it is a relatively new technique. In conclusion, the development of surgical techniques has permitted to minimize deformities and the current trend is that these techniques be as conservative as possible. Thus, lymphoscintigraphy plays an important role in the identification of SLN, contributing to the prevention and minimization of postoperative complications.


Author(s):  
Samuel Córdova-Sánchez ◽  
José Izquierdo-Hernández ◽  
Sergio Salgado-García ◽  
Luz del Carmen Lagunes-Espinoza ◽  
David Jesús Palma-López ◽  
...  

Objective: To evaluate the industrial quality of three sugarcane cultivars in a template cycle at the supply area of “Santa Rosalía de la Chontalpa” sugarcane mill. Design / Methodology / Approach: An experiment was established under a factorial design 3x3 (3 cultivars: CP 72-2086, MEX 79-431 and MEX 69-290; x 3 sampling dates: 330, 390 and 450 DDS, Spanish equivalent for days after sowing) on an Eutric Fluvisol soil. In each plantation, a sample of 10 stems with three replications was collected to determine the industrial quality by polarimetry. Results: The industrial quality of the evaluated cultivars only differed statistically in terms of the percentage of purity, MEX 79-431 was the one that presented the lowest value for this variable. At 450 DDS, the highest value was observed for °Brix (17.28), POL percentage (14.92), purity (86.44%). The values obtained in the present study for the quality of juice in the evaluated cultivars are within the range of the standard values established for Mexico. Limitations / Implications: Polarimetry is still the method used by most of the sugar mills in Mexico, even if other more environmental-friendly methodologies exist. Findings / Conclusions: The trend line that best fit to MEX 69-290 and MEX 79-431, for °Brix, POL and purity, was a linear polynomial and to CP 72-2086, a polynomial quadratic. Fresh stems and reducing sugars showed best fit with an inverse polynomial. °Brix presented strong and positive correlation with POL (R = 0.99**); and strong and negative with reducer sugars (R = -0.95**) and fresh stem humidity (R = -0.91**).


2008 ◽  
Vol 56 (3) ◽  
pp. 684-692 ◽  
Author(s):  
Namgon Kim ◽  
Jeonghoon Yoon ◽  
Sungjoon Cho ◽  
Jeiwon Cho ◽  
Changyul Cheon ◽  
...  

Author(s):  
Niccolo Traverso Ziani ◽  
Fabio Cavaliere ◽  
Karina Guerrero Becerra ◽  
Maura Sassetti

The simplest possible structural transition that an electronic system can undergo is Wigner crystallization. The aim of this short review is to discuss the main aspects of three recent experimets on the one dimensional Wigner molecule, starting from scratch. To achieve this task, the Luttinger liquid theory of weakly and strongly interacting fermions will be shortly addressed, together with the basic properties of carbon nanotubes that are require. Then, the most relevant properties of Wigner molecules will be addressed, and finally the experiments will be described.


1988 ◽  
Vol 1 (21) ◽  
pp. 153
Author(s):  
Masato Yamamoto ◽  
Kazumasa Mizumura ◽  
Taiji Endo ◽  
Naofumi Shiraishi

The object of this present research is to study probabilistic design of armor blocks protecting composite breakwaters and to produce optimum design methodology for S-shaped breakwaters in terms of failure probability and construction cost. Failure probability in the vicinity of the still water level is greatest in the case of uniform sloped breakwaters. Therefore,S-shaped breakwaters of which the slope near the still water level is milder have a reduced risk of damage compared to uniform sloped ones. The optimum design index presents good economics and reliability in rubble-mound breakwater design.


Author(s):  
SARIKA KHALADKAR ◽  
SARITA MALUNJKAR ◽  
POOJA SHINGOTE

Secure environments protect their resources against unauthorized access by enforcing access control mechanisms. So when increasing security is an issue text based passwords are not enough to counter such problems. The need for something more secure along with being user friendly is required. This is where Image Based Authentication (IBA) comes into play. This helps to eliminate tempest attack, shoulder attack, Brute-force attack. Using the instant messaging service available in internet, user will obtain the One Time Password (OTP) after image authentication. This OTP then can be used by user to access their personal accounts. The image based authentication method relies on the user’s ability to recognize pre-chosen categories from a grid of pictures. This paper integrates Image based authentication and HMAC based one time password to achieve high level of security in authenticating the user over the internet.


2021 ◽  
Vol 7 (4) ◽  
pp. 821-833
Author(s):  
Sajida Awais ◽  
Atif Ashraf ◽  
Ghulam Shabir

Purpose: The present study aims to explore the role of viewer’s reactivity of entertainment and empathy in their perception of violence against women among viewers of Lahore, Pakistan. The supplementary aim was also formulated to gain more clear insight which is the role of viewers’ gender in viewer’s reactivity and perception of violence against women. Design/Methodology/Approach Quantitative method was used in the study.  Sample was consisted of 500 viewers of the thirty dramas serials of Geo, ARY Digital and Hum TV which presented violence against women. The participants were drawn through purposive and snowball sampling strategies.  The sample has 233 male participants and 267 female participants. Findings: The findings indicated that viewer’s reactivity of both enjoyment and empathy correlated with perception of violence against women. Gender differences were found only for the one sub scale of perception (i.e., domination). Implications/Originality/Value: The findings highlighted that perception of violence against women was more inclined towards active violence being portrayed by the entertainment channels and chances to imitate the same behavior in society cannot be ruled out.


2018 ◽  
Vol 55 (1) ◽  
pp. 38-41
Author(s):  
Serban Talpos ◽  
Tareq Hajaj ◽  
Costin Timofte ◽  
Mircea Rivis ◽  
Felicia Streian ◽  
...  

Implants and biomaterials used in hard and soft oral tissue augmentation are very complex, but predictable to use nowadays, as the technological advances haven�t skipped this field of medicine. Cases that were impossible to treat with implant retained fixed prosthesis some years ago, have become the daily practice of oral surgeons and dentists around the world. The new user-friendly products, together with simplified protocols, increased the practitioners� predictability and success rate, thus the biomaterial industry took a huge leap forward. As the biomaterial industry keeps developing continuously, making better and safer products, the surgical and prosthetic protocols evolve and change as well. On this matter, the implant placement has become safer, using digital surgical guides. Guided implant placement doesn�t just allow the practitioner place the implant in the patient�s bone, but, moreover, it helps him place it in the correct, 3D, prosthetic position. And, thus, guiding the future bone augmentation and regeneration as well, accordingly. So, the implant placement has shifted from bone-orientated to prosthetic-orientated, offering at the same time a better primary stability for the implants, due to the prior planning. The present clinical study aims to analyze the outcome of the digital guided protocol. Unlike the free-handed surgery, the digital guided surgery allows dentists and oral surgeons to place implants according to the future prosthetic position of the crowns, even in conditions of alveolar ridges with bone resorption. Moreover, it makes possible the �one day implant� concept, the dental technician being able to create the provisional crown/s in advance, knowing precisely the future position of the implant placement. So, at the time of the surgery, the provisional crown is also put in place, guiding the soft and hard tissue healing and also giving the patient a greater satisfaction.


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