A modified beam-to-earth transformation to measure short-wavelength internal waves with an acoustic Doppler current profiler

Author Posting. © American Meteorological Society 2005. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 22 (2005): 583–591, doi:10.1175/JTECH1731.1.The algorithm used to transform velocity signals from beam coordinates to earth coordinates in an acoustic Doppler current profiler (ADCP) relies on the assumption that the currents are uniform over the horizontal distance separating the beams. This condition may be violated by (nonlinear) internal waves, which can have wavelengths as small as 100–200 m. In this case, the standard algorithm combines velocities measured at different phases of a wave and produces horizontal velocities that increasingly differ from true velocities with distance from the ADCP. Observations made in Massachusetts Bay show that currents measured with a bottom-mounted upward-looking ADCP during periods when short-wavelength internal waves are present differ significantly from currents measured by point current meters, except very close to the instrument. These periods are flagged with high error velocities by the standard ADCP algorithm. In this paper measurements from the four spatially diverging beams and the backscatter intensity signal are used to calculate the propagation direction and celerity of the internal waves. Once this information is known, a modified beam-to-earth transformation that combines appropriately lagged beam measurements can be used to obtain current estimates in earth coordinates that compare well with pointwise measurements.A. Scotti was partially supported by ONR Grants N00014-03-1-0553 and N00014-01-1- 0172, B. Butman and P. Alexander by the U.S. Geological Survey, and R. Beardsley by the WHOI Smith Chair and ONR Grant N00014-98-1-0210. S. Anderson received partial support from ONR (Grant N00014-97- 1-0158). The Massachusetts Bay Internal Wave Experiment was jointly supported by ONR and USGS

Prediction of emerging technologies based on analysis of the US patent citation network

Abstract The network of patents connected by citations is an evolving graph, which provides a representation of the innovation process. A patent citing another implies that the cited patent reflects a piece of previously existing knowledge that the citing patent builds upon. A methodology presented here (1) identifies actual clusters of patents: i.e., technological branches, an

Unsteady hydrodynamics of a full-scale tidal turbine operating in large wave conditions

Tidal turbines operate in a highly unsteady environment, which causes large-amplitude load fluctuations to the rotor. This can result in dynamic and fatigue failures. Hence, it is critical that the unsteady loads are accurately predicted. A rotor's blade can experience stall delay, load hysteresis and dynamic stall. Yet, the significance of these effects for a full-scale axial-flow turbine are unclear. To investigate, we develop a simple model for the unsteady hydrodynamics of the rotor and consider field measurements of the onset flow. We find that when the rotor operates in large, yet realistic wave conditions, that the load cycle is governed by the waves, and the power and blade bending moments oscillate by half of their mean values. While the flow remains attached near the blade tip, dynamic stall occurs near the blade root, resulting in a twofold overshoot of the local lift coefficient compared to the static value. At the optimal tip-speed ratio, the difference between the unsteady loads computed with our model and a simple quasi-steady approximation is small. However, below the optimal tip-speed ratio, dynamic stall may occur over most of the blade, and the maximum peak loads can be twice those predicted with a quasi-steady approximation

Professional development and sustainable development goals

Professional development is defined as a consciously designed systematic process that helps professionals to attain, utilize, and retain knowledge, skills, and expertise. It is simply a process of obtaining skills, qualifications, and experience that help in advancement in one’s career. In the field of education, it is defined as the process of improving staff skills and competencies needed to produce outstanding performance of students. It also refers to a process of improving an organization’s staff capabilities through access to education and training opportunities for better output. Professional development can include a variety of approaches such as formal and informal education, vocational, specialized, or skill-based training, or advanced professional learning

EVALUASI SIMPANG BERSINYAL PADA JALAN AW. SHARANIE – JALAN YOS SUDARSO I DI KOTA SANGATTA

Sektor perhubungan, khususnya darat merupakan salah satu sektor yang sangat penting dalam pembangunan, mengingat sektor ini akan terus berkembang sejalan dengan pertumbuhan jumlah penduduk, kebutuhan perjalanan dan aktifitas masyarakat yang menyebabkan meningkatnya arus lalu lintas sehingga kebutuhan akan jalan raya sebagai sarana perhubungan darat akan semakin meningkat. Dalam perkembangannya jalan yang merupakan sarana perhubungan tidak mampu berfungsi karena arus lalu lintas yang makin padat sehingga terjadi berbagai permasalahan seperti terjadi kemacetan, biaya perjalanan mahal, waktu tempuh yang lama serta kenyamanan lalu lintas tidak terjamin.Persimpangan jalan adalah simpul pada jaringan jalan dimana ruas jalan bertemu dan lintasan arus kendaraan berpotongan. Lalu lintas pada masing-masing kaki persimpangan menggunakan ruang jalan pada persimpangan secara bersama-sama dengan lalu lintas lainnya. Olehnya itu persimpangan merupakan faktor yang paling penting dalam menentukan kapasitas dan waktu perjalanan pada suatu jaringan jalan khususnya di daerah-daerah perkotaan.Persimpangan merupakan tempat sumber konflik lalu lintas yang rawan terhadap kecelakaan karena terjadi konflik antara kendaraan dengan kendaraan lainnya ataupun antara kendaraan dengan pejalan kaki. Oleh karena itu merupakan aspek penting didalam pengendalian lalu lintas. Simpang sebagai pertemuan dari beberapa ruas jalan merupakan titik kritis pada jaringan jalan. Pada bagian kritis ini, potensi permasalahan yang dapat terjadi digambarkan dengan banyaknya konflik arus lalu lintas sebagai akibat bertemuan beberapa arus dari berbagai arah pergerakan kendaraan pada titik yang sama di simpang. Persimpangan Bersinyal Jalan AW. Sharanie - Jalan Yos Sudarso I di kota Sangatta berada dalam wilayah Kelurahan Sangatta, Kecamatan Sangatta Utara. Persimpangan ini pada jam-jam sibuk di pagi dan sore hari merupakan persimpangan yang sering terjadi antian atau tundaan akibat adanya aktifitas kegiatan warga yang berangkat dan pulang bekerja disebabkan sebelah Utara Kota Sangatta merupakan simpang empat sangat padat. Seiring dengan bertambahnya volume kendaraan, jumlah penduduk dan adanya aktifitas kegiatan maka persimpangan ini semakin meningkat pula kendaraan yang melewatinya