Rip current rescues on unguarded beaches

Rip currents are the greatest danger at surf beaches. Professional lifeguards rescue tens of thousands of people every year at U.S. beaches, but only a small percentage of the nation’s beaches are guarded. Oftentimes it is a young person who is caught in a rip current, and a bystander will attempt a rescue without a flotation device. The U.S. Lifesaving Association strongly suggests that this kind of rescue should not be undertaken because too often the rescuer will drown. Some coastal towns such as Cocoa Beach in Florida are now posting ring buoys on their unguarded beaches with the warning to throw, but not to go into the water. Ring buoys of two different weights were tested for efficiency when thrown in terms of distance and accuracy. The participants threw the ring buoys two different ways: one way of their choosing (un-instructed) and second by Red Cross recommendation (instructed). The buoyancy was also tested for each buoy. While these flotation devices have some merit, they clearly have limitations.

CHARACTERISTICS OF WATER RING COMPRESSOR MACHINES VACUUM FISH PUMPING UNITS

The operation of the Samson KS910 pump under various conditions is investigated. The values of empirical constants in mathematical dependencies for calculating pump characteristics were found using the least squares method based on published experimental data. The results of calculating the productivity and power consumption of the Samson KS910 in the vacuum pump mode depending on the pressure in the working chamber at different values of the rotor speed and pressure in the working chamber are presented.

Unraveling nucleation pathway in methane clathrate formation

Methane clathrates are widespread on the ocean floor of the Earth. A better understanding of methane clathrate formation has important implications for natural-gas exploitation, storage, and transportation. A key step toward understanding clathrate formation is hydrate nucleation, which has been suggested to involve multiple evolution pathways. Herein, a unique nucleation/growth pathway for methane clathrate formation has been identified by analyzing the trajectories of large-scale molecular dynamics (MD) simulations. In particular, ternary water-ring aggregations (TWRAs) have been identified as fundamental structures for characterizing the nucleation pathway. Based on this nucleation pathway, the critical nucleus size and nucleation timescale can be quantitatively determined. Specifically, a methane hydration layer compression/shedding process is observed to be the critical step in (and driving) the nucleation/growth pathway, which is manifested through overlapping/compression of the surrounding hydration layers of the methane molecules, followed by detachment (shedding) of the hydration layer. As such, an effective way to control methane hydrate nucleation is to alter the hydration layer compression/shedding process during the course of nucleation.

PERFORMANCE OF HIGH-POWER VACUUM FISH PUMPING UNITS

The article describes the features of modeling the stages of pumping a waterfish mixture using a water-ring vacuum pump. The dynamics of pressure changes in reservoir during pump operation for different time intervals is considered. Solutions of the corresponding differential equations are obtained using the numerical method. The calculated characteristics of the process of water-fish mixture pumping into the receiving container are presented.

STAGES OF VACUUM FISH-PUMP UNIT OPERATION

The article describes the features of modeling the stages of pumping a water- fish mixture using a water-ring vacuum pump. The dynamics of pressure changes in the working capacity during pump operation for different time intervals is considered. Solutions of the corresponding differential equations are obtained using the numerical method. The results of calculating the characteristics of the process of pumping the water- fish mixture into the receiving container are presented.

K2 SHAFT WATER RING INSTALLATION AT KENCANA UNDERGROUND PT NUSA HALMAHERA MINERAL

ABSTRAK Kencana 2 (K2) Shaft sebagai salah satu jalur lubang terbuka vertikal pada fasilitas Kencana UG PTNHM terdapat rembesan air 8 l/s melalui kontak sambungan (cold joint) antara dinding concrete shaft pada beberapa level. Air tersebut membasahi jalur winder cage dan tali pengaman dari winder shaft dan berakibat masalah korosif menyebabkan terganggu jalur evakuasi yang berpotensi terjadi gangguan produksi jika tidak di atasi. Pengusulan pemasangan talang air khusus pada dinding shaft terhubung langsung pada pipa services DN150 yang terpasang sepanjang 284m menuruni dinding shaft. Talang air khusus ini terbuat dari material galvanis yang kuat dan tahan lama. Pipa services DN150 terhubung langsung menuju stasiun #3 pompa KL. Dari hasil pengamatan setelah terpasang talang air khusus ini, tidak terjadi lagi rembesan air yang masuk kedalam ruangan winder cage dan tali winder, serta kondisi rembesan air pada dinding shaft telah dialirkan menuju stasiun pompa KL sehingga area K2 shaft menjadi kering Kata Kunci: Modifikasi Shaft Winder Platform, Pemasangan Talang Air Khusus. ABSTRACT The Kencana 2 (K2) Shaft as a vertical open hole UG facility at Kencana UG PTNHM has approximately 8 l/s inflow of water leaking through the cold joints in the concrete liner at various locations. This water saturates the winder cage room and the guide ropes in the winder of shaft and has caused corrosion issues causing the escape route to be compromised leading to a production loss if not take prevention action. It was proposed to install a prefabricated moulded water ring on the wall of the shaft to direct water to a DN150 services steel pipe line that runs down to a 284m depth down of the shaft wall. This water ring using galvanised material and it is tough and durable. The services pipe DN150 would then be piped away from bottom of the K2 shaft to a nearby KL pump station #3. From observation result after water ring installed that there was no water rain into winder cage and rope, and it also the dripping down of the water along the shaft concrete wall was divert throught to the KL pump station so that the K2 shaft area was getting dry. Key Word: Modification Shaft Winder Platform, Water Ring Installation.