A simple method to produce fragment seedstock for aquaculture of Pterocladiella capillacea (Gelidiales, Rhodophyta)

Raw material of gelidioid red algae yielding high-quality agar has been in short supply due to overharvesting, but in situ farming of gelidioids has not been practical due to their slow growth. To produce vegetative seedstock of a cosmopolitan species, Pterocladiella capillacea, we investigated the number and length of regenerated branches arising from sectioned fragments during 3 weeks of laboratory culture at 10, 15, 20, and 25°C. All sectioned fragments formed axis-like branches mostly from the upper cut edge and stolon-like branches mostly from the lower cut edge, showing a high capacity of regeneration and intrinsic bipolarity. At 20°C, the number of regenerated branches increased to 2.74 ± 1.29 on the upper cut edge and 4.26 ± 2.66 on the lower cut edge. Our study reveals that the use of fragments bearing regenerated branches as seedstock can be a simple method to initiate fast propagation for mass cultivation in the sea or outdoor tank.

Influence of the laser cutting front geometry on the striation formation analysed with high-speed synchrotron X-ray imaging

The generation of low surface roughness of the cut edge during laser beam cutting is a challenge. The striation pattern, which determines the surface roughness, can be distinguished into regular and interrupted striations, the latter resulting in an increased surface roughness. In order to analyse their formation, the space- and time-resolved cutting front geometry and melt film thickness were captured during laser beam fusion cutting of aluminium sheets with a framerate of 1000 Hz by means of high-speed synchrotron X-ray imaging. The comparison of the contours of the cutting fronts for a cut result with regular und interrupted striations shows that the contour fluctuates significantly more in case of interrupted striations. This leads to a strong fluctuation of the local angle of incidence. In addition, the average angle of incidence decreases, which results in an increase of the average absorbed irradiance. Both phenomena, local increase of absorbed irradiance and its dynamic fluctuation, result in a local increase of the melt film thickness at the cutting front which is responsible for the formation of the interrupted striations.

Using the Design of Experiment Method to Develop an Energy Loss Model for Non-Oriented Electrical Steel Alloys

The main scope of the paper is to apply the Design of Experiment (DoE) method and to develop a predictive model of energy losses for non-oriented electrical steels. This approach permits us to determine a mathematical model, which is the predicted response (energy losses) as a function of input data (strip width and peak magnetic polarization) and experimental results. The presented DoE model is based on a classical central composite design of type 2n + 2n + 1 with two-levels (n = 2) and as a consequence only nine experimental points are necessary. The equation system that is associated with the model, generates a surface response equation, which permits the energy loss computation for different values of width strip and peak magnetic polarization. The DoE model was implemented, using different software packages as MathCad, Excel and OriginPro 2018, in the case of two types of electrical steels namely NO20 and M300-35A alloys that are used in small size electrical machines. In this case, the strain hardening phenomena at the cut edge becomes important, due to its negative impact on energy losses. The computed results were compared with the experimental data and errors lower than 5 % were determined.

Establishment of suitable parameters for laser machining based production of polymeric implants

Laser material processing enables precise machining of a wide variety of materials. In order to prevent an excessive heat input, which leads to irreversible material damage, the process parameters have to be adapted to the processed material. To keep the heat load as low as possible, the potential of femtosecond laser technology is exploited. The processing of semi-finished products using femtosecond laser technology is highly depending on the processed material. In this regard, we established a workflow and basic parameters for the processing of polymeric material. The performed parameter study varying cutting speed, cutting gas pressure and pulse energy to optimize the manufacturing process. Scanning electron microscopy (SEM) was utilized to analyze the cutting results, such as cut edge quality or possible melted areas. The established parameter set is also suitable for processing of very filigree material structures as used in innovative medical devices. The SEM analysis of the established parameter set showed that a homogeneous, nonwavy cut edge was created along the kerf.

Studi Rendemen Finir dan Besarnya Limbah Pada Pengupasan Finir dengan Mesin Rotary Lathe Tipe Spindleless

In general, the log-block peeling yield on a rotary lathe machine ranges from 70 - 80% of the log volume in the form of veneer, and the remaining 20-30% is waste. This variation depends on the quality and type (species) of the log of the raw material. The veneer peeling usually consist of the face and back veneer (continuous veneer) ranging from 50% to 70% and core veneer as poly piece veneer ranging from 20 to 30%. Under certain conditions, the waste can reach up to 50% including losses due to rounding, shrinkage of the veneer, cracks, spurs, and pith (log-core). From the description above and several other observations, the research was carried out regarding this matter. There is a way to reduce the amount of waste in log peeling using rotary machines and at the same time increasing the recovery peeling. Thus, it will reduce production costs and increase profits for the company. One of the contributors to a large amount of veneer peeling waste is the use of rotary lathe veneer peeling machines with large spindles which are still widely used in veneer and plywood factories (plymill), especially in Indonesia. So far, on average half of raw logs turn into waste, and 25 percent is contributed by a rotary lathe machine. Meanwhile, on the other hand, the need for plywood products will continue to increase day by day. This is because plywood is one of the most environmentally friendly building materials and comes from renewable natural resources. Along with the development of the plywood industry, the increase of raw material needs is inevitable. So, waste products will also continue to increase too. In this regard, there must be fundamental changes in this industry, including the use of rotary lathe without spindles as the substitute from the conventional machine. In relevance to this situation, this research was directed with the aim of knowing the yield and amount of veneer peeled by a spindle-less rotary lathe machine and at the same time to find out the waste it produces. So, this information can later become a consideration for stakeholders to replace the old rotary lathe with a type spindle-less without a doubt. The results show that veneer peeling using a spindle-less rotary lathe machine increases the yield of the veneer and reduce the amount of waste. Most of the peeling results are in the form of a veneer consisting of 58.83% continuous/endless veneer for the face/back, and 22.83% of poly piece core (odd veneer) from the core veneer. The total veneer yield is 81.67%. The remaining were 1.32%, 0.93%, and 16.08% for log-core waste, cut edge finish, and round-up veneer, respectively. The spindle-less rotary lathe machine has provided increased yields and significantly reduced the amount of waste. Keywords : Waste, rotary lathe, spindle-less, veneer.

Factorial Analysis of Fiber Laser Fusion Cutting of AISI 304 Stainless Steel: Evaluation of Effects on Process Performance, Kerf Geometry and Cut Edge Roughness

Factorial Design-of-Experiment analyses were applied for conventional and beam oscillation fiber laser cutting of 10 mm thick AISI 304 stainless steel. Considered factors in case of the conventional process with a static beam involve both laser and cutting gas parameters, in particular the laser power, the focal plane position, the cutting gas pressure, the nozzle stand-off distance as well as the nozzle diameter. The conducted trials were evaluated with respect to the achievable cutting speed, the cut kerf geometry and the cut edge roughness. Noticeable correlations between cut edge roughness and cut kerf geometry stimulated the development of a corresponding Computational Fluid Dynamics (CFD) model of the cutting gas flow through the kerf. A specific approach of data synchronization revealed that the experimentally determined roughness values do well correlate with numerically computed values of the backward directed component of the gas-induced shear stress and that the cut kerf geometry as internal process-inherent boundary condition influences relevant cutting characteristics more than controllable external cutting gas parameters. Finally, effects of circular beam oscillation were investigated by an additional factorial analysis considering the laser power, the focal plane position, the oscillation frequency and the oscillation amplitude as factors. The results demonstrate the potential of beam oscillation techniques for quality improvements in laser cutting.