| 1. |
- Ahuja, Gaurav, 1978
(författare)
-
Application of a Sandwich Construction on a Superstructure of a High Speed Ferry
- 2007
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Usage of light weight materials has gained momentum in the marine market in the last few decades. This rise has lead to some ships using parts fabricated out of materials like glass and carbon fibre. A major advantage of the usage of light weight materials in shipping is that it either increases the cargo carrying capacity of the vessel or reduces the fuel consumption or both. Different kinds of problems and issues need to be addressed when using new and innovative materials. These problems range from issues of both technical and non-technical nature. Technical problems are generally related to structural strength, fire safety and joining materials of different kinds. Non-technical issues would include maintenance and most importantly getting a good idea about the economics and pay back time of using light weight materials.This thesis discusses the possibility of using light weight materials like glass and carbon fibre as a super structure on board the 88 m long Stena Carisma catamaran. Sandwich construction is the recommended method of employing light weight construction. Different concepts have been generated using the spacing of pillars and the materials used. Analytical structural analysis for each concept is performed. The concept that has the lightest weight is further evaluated using the finite element (FE) method. Thus both analytical calculations and FE analyses have been used to confirm the feasibility of having a sandwich superstructure for the vessel. Both static and dynamic analysis are conducted for the study of the superstructure. Classification society regulations are used as the base to do the structural calculations. Considering the various criteria of the society, a structural optimisation is also performed. Based on the results obtained from the analysis performed, it is shown that a conventional aluminium superstructure for such a vessel can be replaced by innovative light weight materials. This replacement would be accompanied by a reduction in the weight of the vessel as well as by reduced maintenance requirement. Thus there is a two fold benefit from application of light weight materials. This work includes the structural analysis of the superstructure made of composite materials and also about the interaction of the two materials namely aluminium and the composites. FE analysis has been done to understand the structural behaviour of the structure. This analysis is carried out in ANSYS.
|
|
| 2. |
|
|
| 3. |
- Ahuja, Gaurav, 1978, et al.
(författare)
-
Sandwich Construction - Application on a superstructure
- 2005
-
Ingår i: INMAT 2005. ; , s. 11-
-
Konferensbidrag (refereegranskat)abstract
- The use of light weight materials is increasing at a rapid pace in the present day industry. Automobiles, aircrafts, ships and several other fields are increasingly finding large potential in using lighter materials for construction. In the past few years a number of water borne means of transportation have been moulded from composites. For ships, this leads to reducing the light weight and thus an increase in the capacity of the payload. A reduction in the light weight of the ship implies more cargo and more revenue generation for the ship owner. Over an average lifetime of 25 years, the amount of revenue generated could be significant, due to which a number of ship owners are giving a serious thought to the usage of light weight materials in shipping. Stena Line, a Swedish shipping company has a number of passenger ferries running in the European region. They are also the proud owners of the HSS series of ships, which are unique as they are catamarans made completely in aluminium. Being the pioneers in the shipping industry, they have considered the possibility of having a sandwich superstructure for one of their ferries, HSS 900. This paper looks into the preliminary design of the structure under DNV regulations. While fire safety is also part of the project, this paper focuses on the structure. Different kinds of fibres, resins and cores could be used for making the sandwich construction. The fibre making the faces could be E-glass, S-glass, carbon fibre etc, the resin systems also provide a variety of options like the polyesters, vinyl esters and phenolics. Similarly the core material could be honeycomb, PVC or PU. In this paper, possibilities of using these materials for the making the superstructure has been looked into. A preliminary calculation shows how much in terms of light weight of the vessel could be saved if sandwich construction is used. As it is weight critical approach that is the driving factor in using light weight materials, an optimization of the structure by breaking it up into sandwich panel, spacing of the transverses and longitudinal has also been performed. While optimizing the sandwich panel, four major criteria of maximum normal stress, maximum shear stress, wrinkling stress and maximum allowed deflection have been explored. The limit point where all the four requirements are met and the weight is minimum possible has been considered as the optimum point. All in all it is a sandwich superstructure, which has been optimized for weight.
|
|
| 4. |
- Alluri, Nagamalleswara Rao, et al.
(författare)
-
Crystallinity modulation originates ferroelectricity like nature in piezoelectric selenium
- 2022
-
Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 95
-
Tidskriftsartikel (refereegranskat)abstract
- Modern room temperature ferroelectrics/piezoelectrics significantly impact advanced nanoelectronics than conventional chemical compounds. Changes in crystallinity modulation, long-range order of atoms in metalloids permits the design of novel materials. The ferroelectric like nature of a single element (selenium, Se) is demonstrated via in-plane (E perpendicular to(ar) to the Se helical chains in micro-rod (MR)) and out-of-plane (E parallel to(el) to the Se helical chains in MR) polarization. Atomic electron microscopy shows large stacks of covalently bound Se atoms in a c-axis orientation for tip bias voltage-dependent switchable domains with a 180 degrees phase and butterfly displacement curves. The single crystalline Se MR has a high in-plane piezoelectric coefficient of 30 pm/V relative to polycrystalline samples due to larger grains, crystal imperfections in MR, and tuned helical chains. The energy conversion of a single Se-MR demonstrated via d(13), d(12) (or d(15)) piezoelectric modes.
|
|
| 5. |
- Beal, Jacob, et al.
(författare)
-
Robust estimation of bacterial cell count from optical density
- 2020
-
Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
|
|
| 6. |
- Frank, Stefan, et al.
(författare)
-
yylncT Defines a Class of Divergently Transcribed lncRNAs and Safeguards the T-mediated Mesodermal Commitment of Human PSCs.
- 2019
-
Ingår i: Cell stem cell. - : Elsevier BV. - 1875-9777 .- 1934-5909. ; 24:2
-
Tidskriftsartikel (refereegranskat)abstract
- Human protein-coding genes are often accompanied by divergently transcribed non-coding RNAs whose functions, especially in cell fate decisions, are poorly understood. Using an hESC-based cardiac differentiation model, we define a class of divergent lncRNAs, termed yin yang lncRNAs (yylncRNAs), that mirror the cell-type-specific expression pattern of their protein-coding counterparts. yylncRNAs arepreferentially encoded from the genomic loci ofkey developmental cell fate regulators. Most yylncRNAs are spliced polyadenylated transcripts showing comparable expression patterns invivo inmouse and in human embryos. Signifying theirdevelopmental function, the key mesoderm specifier BRACHYURY (T) is accompanied by yylncT, whichlocalizes to the active T locus during mesoderm commitment. yylncT binds the de novo DNA methyltransferase DNMT3B, and its transcript is required for activation of the T locus, with yylncTdepletion specifically abolishing mesodermal commitment. Collectively, we report a lncRNA-mediated regulatory layer safeguarding embryonic cell fate transitions.
|
|
| 7. |
- Gaurav, Kumar, et al.
(författare)
-
Trans-polyacetylene based organic spin valve for a multifunctional spin-based device : A first principle analysis
- 2022
-
Ingår i: JOURNAL OF SCIENCE-ADVANCED MATERIALS AND DEVICES. - : Elsevier. - 2468-2284 .- 2468-2179. ; 7:3
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon-based materials are the promising candidates for the design of multifunctional spintronic devices, owing to their fascinating inherent attributes such as the ballistic transport nature, long spin coherence time, etc. Here, we report the spin-dependent electron transport properties of a transpolyacetylene channel sandwiched between two semi-infinite hydrogen-passivated zigzag graphene nanoribbon (ZGNR) electrodes within the framework of spin-polarized density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalisms. The proposed device exhibits an excellent spin-dependent transport behavior within the bias window of [-0.5 V, 0.5 V]. In parallel configuration (PC), the device offers an ideal spin filtration efficiency of almost 100% within the bias range of [-0.4 V, 0.4 V], and in antiparallel configuration (APC), it exhibits negative differential resistance (NDR), dual-spin rectification, and dual-spin filtration effects. Also, a high tunnel magnetoresistance (TMR) of 1.2 x 10(5)% is achieved. To validate the aforementioned effects, the transmission spectra along with the area enclosed by the curve, eigenvalues, eigenstates, and quantum conductance have also been analyzed. In addition, the impact of hybridization and torsion defects on the spin-dependent transport phenomenon through trans-polyacetylene has been investigated. Furthermore, the modelled device is observed to exhibit the spin Seebeck effect in PC under the influence of temperature gradient. The proposed device may stand as a good contender for various spintronic and spin caloritronic applications. (C) 2022 Vietnam National University, Hanoi. Published by Elsevier B.V.
|
|
| 8. |
- Gerkin, Richard C., et al.
(författare)
-
Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms
- 2021
-
Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 46
-
Tidskriftsartikel (refereegranskat)abstract
- In a preregistered, cross-sectional study, we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0–100 visual analog scales (VAS) for participants reporting a positive (C19+; n = 4148) or negative (C19−; n = 546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19− groups exhibited smell loss, but it was significantly larger in C19+ participants (mean ± SD, C19+: −82.5 ± 27.2 points; C19−: −59.8 ± 37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC = 0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms (e.g., fever). Olfactory recovery within 40 days of respiratory symptom onset was reported for ~50% of participants and was best predicted by time since respiratory symptom onset. We find that quantified smell loss is the best predictor of COVID-19 amongst those with symptoms of respiratory illness. To aid clinicians and contact tracers in identifying individuals with a high likelihood of having COVID-19, we propose a novel 0–10 scale to screen for recent olfactory loss, the ODoR-19. We find that numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4 < OR < 10). Once independently validated, this tool could be deployed when viral lab tests are impractical or unavailable.
|
|
| 9. |
- Kuo, Chao-Chung, et al.
(författare)
-
Detection of RNA-DNA binding sites in long noncoding RNAs.
- 2019
-
Ingår i: Nucleic acids research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 47:6
-
Tidskriftsartikel (refereegranskat)abstract
- Long non-coding RNAs (lncRNAs) can act as scaffolds that promote the interaction of proteins, RNA, and DNA. There is increasing evidence of sequence-specific interactions of lncRNAs with DNA via triple-helix (triplex) formation. This process allows lncRNAs to recruit protein complexes to specific genomic regions and regulate gene expression. Here we propose a computational method called Triplex Domain Finder (TDF) to detect triplexes and characterize DNA-binding domains and DNA targets statistically. Case studies showed that this approach can detect the known domains of lncRNAs Fendrr, HOTAIR and MEG3. Moreover, we validated a novel DNA-binding domain in MEG3 by a genome-wide sequencing method. We used TDF to perform a systematic analysis of the triplex-forming potential of lncRNAs relevant to human cardiac differentiation. We demonstrated that the lncRNA with the highest triplex-forming potential, GATA6-AS, forms triple helices in the promoter of genes relevant to cardiac development. Moreover, down-regulation of GATA6-AS impairs GATA6 expression and cardiac development. These data indicate the unique ability of our computational tool to identify novel triplex-forming lncRNAs and their target genes.
|
|
