Nonlinear vibration behaviors of marine rotor system coupled with floating raft-airbag-displacement restrictor under ship heaving motion

To study the nonlinear vibration behaviors of rotor system coupled with floating raft-airbag-displacement restrictor under ship heaving motion, the dynamic model is established considering the effect of heaving motion, its steady-state responses are numerically obtained using Runge-Kutta method and the results are surveyed by tools such as the spectrum waterfall diagram, time-domain response, frequency-domain response, axis orbit, and Poincaré map. The effects of rotating speed, ship heaving amplitude, and its frequency on the nonlinear dynamic behavior of the system are mainly studied. The results show that the responses of the rotor and raft are of obvious nonlinear behaviors such as amplitude jumping, bifurcation, and chaos due to the effects of nonlinear oil film force and ship heaving motion. With the increase of rotating speed, the motion of rotor and raft presents quasi-periodic and chaotic vibrations. Ship heaving amplitude and its frequency all have great effect on the vibration of rotor and raft; as heaving amplitude or frequency increases, the motion state of rotor and raft changes, and the amplitude of raft increases significantly. The displacement restrictor can effectively limit the vibrating displacements of the raft when ship heaving amplitude or its frequency is large.

The Impact of LED Light Spectrum on the Growth, Morphological Traits, and Nutritional Status of ‘Elizium’ Romaine Lettuce Grown in an Indoor Controlled Environment

The study examined the influence of light quality on the growth and nutritional status of romaine lettuce grown in deep water culture with a floating raft system using two different nutrient solutions. Four spectra of LED light were used with different ratios of R, G, and B lights (80:10:10, 70:10:20, 60:10:30, and 70:18:12). Two nutrient solutions with a low (A) and moderately high (B) nutrient content were used. Regardless of the nutrient solution, the RGB 70:18:12 light promoted the production of leaf biomass as well as inhibited the accumulation of K and Mg in the leaves. Moreover, those plants were characterized by a low Nitrogen Balance Index (NBI) and a high flavonol index. In the last week of cultivation, there was a strong decrease in K, P, and nitrates in the nutrient solution, and an increase in Ca. In the final stage of growth, symptoms of withering of the tips of young leaves (tipburn) were observed on the plants. The most damage was observed on the plants growing under 70:10:20, 70:18:12, and with the higher concentration of minerals in the solution (B).

The combination of irradiation biofertilizer of rhizosphere microbes consortium inoculant (IMR) and inorganic fertilizer on the growth of kale in a floating raft hydroponic system

A hydroponic floating system is a working system where a plant is placed in a floating net pot on the surface of water. In hydroponic systems, the content of inorganic fertilizers contained in the media is the main source of nutrients for plants. The use of biological fertilizers is expected to reduce the dose of inorganic fertilizers applied to hydroponic systems. The main objective of this study was to obtain a combination of inorganic fertilizers with Inoculant of Rhizosphere Microbial Consortium (IMR) and biofertilizer which has the most influence on the N content, growth and production of kale plant. There are five different treatments on hydroponic floating system viz 100% inorganic fertilizer (control), 100% inorganic fertilizer + IMR (Pa), 75% inorganic fertilizer + IMR (Pb), 50% inorganic fertilizer + IMR (Pc), and 25% + IMR (Pd), where 100% inorganic fertilizer is equivalent to 10 mL / L and the amount of IMR given to each treatment was 10 ml/L. The method used in this research was descriptive comparative method, using primary data which is then analysed quantitatively such as using graphs, and T-test. The results of the research showed that giving a combination of 100% biological fertilizer and 50% inorganic fertilizer, can reduce the use of inorganic fertilizers by 50%, and gave the best and significant influence on plant height 34.41 cm, leaves as much as 30 strands, root length 24.27 cm, and the harvest weight 80.97 grams. The combination of 100% biological fertilizer and 50% inorganic fertilizer does not give a combination of N content of the kale plant.

Phytoremediation in Sandpit Lake: Aquaponic

Sandpit Lake in Sukabumi area is a suitable site for developing aquaculture. However due to rapid eutrophication only sustainable aquaculture should be applied. We evaluated the ability of lettuce in reducing nutrients from fish culture. This phytoremediation study was carried out using mesocosm, where lettuce as the phytoremediation agent were grown on vegetable floating raft (VFR) together with 25 fish which were grown underneath it and fed by fish feed. We built three sizes of VFR which were 20, 40 and 60% covered the mesocosm surface. The three sizes VFR were the treatment and the 0% covering served as control. Water quality sampling was carried out two times at day zero and day seven of the experiment. We collected temperature, oxygen, nitrogen, and phosphate data and analyzed them using ANOVA. Our result showed the nitrogen increased inside mesocosm meanwhile orthoposphat decreased. But the size of VFR did not give any effect to the water quality parameter change. However descriptively, we found that 40% of VFR was able to slowdown the nutrien TAN increasing and orthoposphat concentration found to be low. Moreover, it resulted in the highest lettuce survival. We recommend using 40% coverage in employing an aquaponic system in sandpit lake.

Protein Hydrolysate Combined with Hydroponics Divergently Modifies Growth and Shuffles Pigments and Free Amino Acids of Carrot and Dill Microgreens

Microgreens are the new sophisticated commodity in horticulture that boost the human diet with bioactive metabolites and garnish it with colors and tastes. Microgreens thrive well when cultivated in soilless systems, of which closed-loop soilless systems combined with biostimulant application can provide a sustainable, innovative method of growing microgreens. Daucus carota L. and Anethum graveolens L. microgreens were grown in greenhouse conditions implementing a floating raft system combined with a protein hydrolysate of leguminous origin as root application (0.3 mL L−1 nutrient solution). Growth, colorimetric parameters, macronutrients, chlorophylls, carotenoids, carbohydrates, free amino acids, and soluble proteins were assessed. The use of a protein hydrolysate in the nutrient solution engendered an increase in anthocyanins (+461.7%) and total phenols (+12.4%) in carrot, while in dill, the fresh yield (+13.5%) and ascorbic acid (+17.2%) increased. In both species, soluble proteins and total free amino acids increased by 20.6% and 18.5%, respectively. The floating raft system proved to be promising for microgreens and can ease the application of biostimulants through root application. Future research should also investigate the yield and nutritional parameter responses of other species of microgreens with the aim of large-scale sustainable production.

Raft attitude control and elastic deformation suppression technique for large-scale floating raft air spring mounting system

The structure of floating rafts-equipped vessels will be inevitably undermined due to application of large-scale designs. When encountering strong external disturbances, not only the rafts will deviate from the original balanced position but also greater elastic deformation will be generated, which may lead to the relative displacement between devices on rafts and endanger the operation safety of equipment. In this study, a class of raft elastic deformation monitoring and discrimination methods is put forward via analyzing the features of large-scale raft elastic deformation. Air springs layout is optimized through finite element method (FEM). A flexible raft control responding model is established and a novel raft elastic deformation suppression technique is proposed based on air spring pressure parameter identification that adjusts the air spring pressure distribution. The experimental results indicate that this technique can effectively control the attitude of the rafts and reduce elastic deformation, leading to a largely improved control precision and a faster convergence speed of the raft.

Evaluasi tiga sistem budidaya di lahan sempit pada budidaya dua kultivar bayam di Kota Bekasi

AbstrakBudidaya sayuran pada lahan sempit di daerah perkotaan merupakan salah satu upaya pemerintah dalam mewujudkan ketahanan pangan. Tujuan dari penelitian ini adalah untuk mengetahui sistem budidaya tanaman bayam yang paling baik untuk diterapkan pada lahan sempit pekarangan di Kota Bekasi. Percobaan ini telah dilaksanakan pada bulan Agustus hingga September 2020 di areal pemukiman yang berlokasi di Jalan Caringin Raya, Kota Bekasi. Percobaan menggunakan metode Rancangan Acak Kelompok (RAK). Dua kultivar bayam, ‘Maestro’ dan ‘Mira’, dibudidayakan pada tiga sistem budidaya berbeda, yaitu konvensional, vertikultur, dan hidroponik rakit apung yang diulang sebanyak empat ulangan. Hasil penelitian menunjukkan bahwa penanaman bayam pada sistem hidroponik rakit apung menghasilkan pertumbuhan, hasil, kualitas hasil, serta pendapatan yang paling baik dibandingkan dengan sistem budidaya konvensional dan vertikultur.Kata kunci: Hidroponik, hortikultura, sayuran, vertikultur Abstract Vegetable cultivation on limited areas in urban is one of the government's efforts to obtain food security. The purpose of this study was to determine the best amaranth cultivation system to be applied in urban farming system likewise on limited areas in Bekasi City. This experiment was carried out from August to September 2020 in a densely inhabited living area located on Caringin Raya Street, Bekasi. The experiment used a Randomized Block Design. Two cultivars amaranth, ‘Maestro’ and ‘Mira’ were cultivated under treatment of three different cultivation. There were conventional system, verticulture system, and hydroponic floating raft, that repeated four times. The results showed that amaranth cultivation on the floating raft hydroponic produced the best growth, yield, yield quality, and revenue, compared to conventional and verticulture cultivation systems. Keywords: Hydroponic, horticulture, vegetables, verticulture.

Online monitoring for floating raft structure displacement based on optimal placement of measuring points

The structure displacement of the raft of vibration isolation for ships is an important factor that affects shafting alignment accuracy and the safety of the equipment on the raft. In order to realize real-time monitoring of the raft structure displacement, which is the uncertain loadings and complex in shape, a measuring point placement strategy and an online monitoring method based on the displacement parameters to identify the displacement of the raft are proposed. FEM-based simulations for a prototyped raft have been conducted to obtain the displacement contour map. According to the displacement contour map based on displacement gradient and index evaluation, the measuring points have been combined and optimized. Displacement reconstruction principle based on a surface spline interpolation function method has been elaborated and derived. Structure displacement at any point can be obtained by a few measuring points. Finally, a case study of a certain type of floating raft is analyzed by the simulation analysis, and experimental research. The simulation and experimental results verify the validity of the measuring point placement strategy and the average of relative error with a value of less than 4% under different uncertain loadings. This method can effectively solve the problem of online monitoring of floating raft structure displacement under different changing loadings.