Noise and Work Reduction through Remodeling of Stern Tube Assembly in a Shipbuilding Process by Applying TRIZ Theory

This study focuses on the installation of a stern tube which is one of the tasks in shafting installation. The traditional way to set up a stern tube needs more labor input in terms of manpower, work schedule and cost. Not only that, during processing, it requires large boring machinery which generates noise which is harmful to workers’ physical and mental conditions. This study first utilizes problem hierarchy analysis in redefining the problem before finding out the solutions using technical contradiction to work out the feasible solutions. Then, after refining and analyzing the feasible solutions, the feasible solutions were carried out and then an “integrated Stern Tube” was created, which decreased 49% of the cost and 71% of the work period in a dock. This means that the new technique makes it possible for a shipyard to enhance its capacity of building vessels as well as lower the noise effectively. As a result, these improvements add up to a friendlier working environment and lead to a win-win situation between workers and management.

Inexpensive and easy method for 6 fragment Golden Gate Assembly of a modular S/MARs mammalian expression vector and its variants

A basic requirement for synthetic biology is the availability of efficient DNA assembly methods. Numerous methods have been previously reported to accomplish this task. One such method has been reported, which allows parallel assembly of multiple DNA fragments in a one-tube reaction, called Golden Gate Assembly. Here described is a simplified and inexpensive Golden Gate Cloning Protocol in which the amplified PCR fragments that enter the one-step-one-pot reaction are stored in Zymo DNA/RNA Shield at -20 degrees C and thawed whenever needed to be used as fragments or modules in the assembly. The protocol inludes the design step, in which fragments are designed to posses unique overhangs, amplification of modules using a high fidelity polimerase from preexisting plasmids or gene fragments, clean-up of the PCR products (fragments) in one tube, assembly, DpnI digestion for eliminating the background plasmids that remain after the PCR reaction and transformation of the resulting assembly reaction into competent E.coli cells. The protocol eliminates the need for vectors and inserts. The plasmid is build using only PCR products or fragments, with one of them containing the bacterial origin of replication and the antibiotic resitance gene for selection. Multiple modular plasmids can be constructed in just one day with minimal hands-on time.

TssA–TssM–TagA interaction modulates type VI secretion system sheath-tube assembly in Vibrio cholerae

The type VI protein secretion system (T6SS) is a powerful needle-like machinery found in Gram-negative bacteria that can penetrate the cytosol of receiving cells in milliseconds by physical force. Anchored by its membrane-spanning complex (MC) and a baseplate (BP), the T6SS sheath-tube is assembled in a stepwise process primed by TssA and terminated by TagA. However, the molecular details of its assembly remain elusive. Here, we systematically examined the initiation and termination of contractile and non-contractile T6SS sheaths in MC-BP, tssA and tagA mutants by fluorescence microscopy. We observe long pole-to-pole sheath-tube structures in the non-contractile MC-BP defective mutants but not in the Hcp tube or VgrG spike mutants. Combining overexpression and genetic mutation data, we demonstrate complex effects of TssM, TssA and TagA interactions on T6SS sheath-tube dynamics. We also report promiscuous interactions of TagA with multiple T6SS components, similar to TssA. Our results demonstrate that priming of the T6SS sheath-tube assembly is not dependent on TssA, nor is the assembly termination dependent on the distal end TssA–TagA interaction, and highlight the tripartite control of TssA–TssM–TagA on sheath-tube initiation and termination.

Two-Objective Optimization of a Kaplan Turbine Draft Tube Using a Response Surface Methodology

The overall cost of a hydropower plant is mainly due to the expenses of civil works, mechanical equipment (turbine and control units) and electrical components. The goal of a new draft tube design is to obtain a geometry that reduces investment costs, especially the excavation ones, but the primary driver is to increase overall machine efficiency, allowing for a reduced payback time. In the present study, an optimization study of the elbow-draft tube assembly of a Kaplan turbine was conducted. First, a CFD model for the complete turbine was developed and validated. Next, an optimization of the draft tube alone was performed using a design of experiments technique. Finally, several optimum solutions for the draft tube were obtained using a response surface technique aiming at maximizing pressure recovery and minimizing flow losses. A selection of optimized geometries was subsequently post-checked using the validated model of the entire turbine, and a detailed flow analysis on the obtained results made it possible to provide insights into the improved designs. It was observed that efficiency could be improved by 1% (in relative terms), and the mechanical power increased by 1.8% (in relative terms) with respect to the baseline turbine.

Two-Objective Optimization of a Kaplan Turbine Draft Tube Using a Response Surface Methodology

The overall cost of a hydropower plant is mainly due to the expenses for civil works, mechanical equipment (turbine and control units) and electrical components. The goal of a new draft tube design is to obtain a geometry that reduces investment costs, especially the excavation ones, but the primary driver is to increase the overall machine efficiency allowing for reduced payback time. In the present study, an optimization study of the elbow-draft tube assembly of a Kaplan turbine was conducted. A CFD model for the complete turbine has been developed and validated; next, an optimization of the draft tube alone was performed using a Design of Experiments technique; finally, several optimum solutions for the draft tube were obtained using a Response Surface technique aiming at maximizing pressure recovery and minimizing flow losses. A selection of optimized geometries was subsequently post-checked using the validated model of the entire turbine and a detailed flow analysis on the obtained results could make it possible to provide insight into the improved designs. It was observed that efficiency could be improved by 1% (in relative terms), and the mechanical power increased by 1,8% (in relative terms) with respect to the baseline turbine.

Computational Fluid Dynamic Analyses of Flow and Combustion in a Domestic Liquified Petroleum Gas Cookstove Burner—Part I: Design Optimization of Mixing Tube–Burner Assembly

Liquefied petroleum gas (LPG) is commonly used in domestic kitchen due to its low health and environmental impacts and high heat content compared to other traditional fuels. The growing demand of LPG, notwithstanding its limited reserve, influences the need for performance improvement of the LPG cookstoves. In an LPG cookstove, the fuel–air mixture is prepared in a self-aspirated burner, and burns as a rich premixed flame above the burner. The fuel–air ratio of the reactant mixture influences the burning characteristics and thermal efficiency of the cookstove. This part of work deals with a numerical study of flow and mixing characteristics in the mixing tube and burner assembly of a domestic LPG cookstove. The fuel is injected axially through a narrow nozzle inside the mixing tube causing entrainment of ambient air through the side ports and the end port. The effects of different side-port geometry, nozzle position, inlet fuel pressure, and nozzle throat diameter on the air ingress have been systematically investigated, and the optimum design has been identified. Results of the study provide important information on the design of the practical nozzle and mixing tube assembly of high-efficiency LPG stoves.