A mathematical model of the CH-53 helicopter

A mathematical model suitable for real time simulation of the CH-53 helicopter is presented. This model, which is based on modified nonlinear classical rotor theory and nonlinear fuselage aerodynamics, will be used to support terminal-area guidance and navigation studies on a fixed-base simulator. Validation is achieved by comparing the model response with that of a similar aircraft and by a qualitative comparison of the handling characteristics made by experienced pilots

The natural resources of Bolinas Lagoon: their status and future

This publication is an integral part of the Department's high-priority inventory and assessment of coastal marshland and tideflat resources. It is intended as a guide for citizens, planners, administrators, and all others interested in the use and development of coastal lands and waters. Although the resources and problems of Bolinas Lagoon have probably been the subject of more biological and physical investigations than any small estuarine area of the California coast, many of the pertinent reports and information are not readily available to the public. Consequently, it is one purpose of this report to summarize the lagoon's history, ecological attractions, educational values and the problems facing its continued existence. At the same time, it should provide concerned citizens with a knowledge of the sources of additional and more specific information. Publication of this report is consistent with the obligation of the Department of Fish and Game to do everything in its power to protect and maintain the State's fish and wildlife resources. Therefore, its purpose transcends local issues on pollution and development, and the Department is, in fact, submitting a report to the people on the status and future of part of its inheritance and the dowry of coming generations. The report is the third of a scheduled series. It follows similar releases on Upper Newport Bay (Orange County) and Goleta Slough (Santa Barbara county) in March and June of 1970. Documentation of the resources of other critical areas is in progress. There will be future reports of this nature on Elkhorn Slough, Morro Bay, Tomales Bay, Humboldt Bay, and highly threatened marshlands in southern California. (137 pp.

Rapid Macrocell Tests of Enduramet® 32 Stainless Steel Bars

The corrosion resistance of EnduraMet® 32 stainless steel bars was evaluated using the rapid macrocell test outlined in Annexes A1 and A2 of ASTM A955-10. Based on the test results, the EnduraMet® 32 stainless steel bars satisfy the requirements of ASTM A955-10

Rapid Macrocell Tests of Enduramet® 33, Enduramet® 316LN, and Endurament® 2205 Stainless Steel Bars

The corrosion resistance of EnduraMet® 33, EnduraMet® 316LN, and EnduraMet® 2205 stainless steel reinforcing bars is evaluated using the rapid macrocell test outlined in Annexes A1 and A2 of ASTM A955-10. Based on the test results, all three types of stainless steel satisfy the requirements of ASTM A955-10

Rapid Macrocell Tests of LDX 2101® Stainless Steel Bars

The corrosion resistance of LDX 2101® duplex stainless steel bars is evaluated using the rapid macrocell test specified in Annex A2 of ASTM A955-09b and compared to the performance of 2205 pickled stainless steel (2205p). LDX 2101® bars were tested in the asreceived condition as well as after submersion in simulated concrete pore solution with a pH of 13.4 for two weeks prior to testing. The LDX 2101® stainless steel bars meet the requirements of ASTM A955-09b, exhibiting limited staining and slight corrosion on the bars in salt solution with a maximum individual corrosion rate of 0.44 μm/yr and a maximum average corrosion rate of 0.10 μm/yr. No significant difference was observed in the behavior between bars tested in the as-received condition and bars tested after submersion in simulated concrete pore solution. The 2205p bars exhibited no visible corrosion products on the bars in salt solution and no measureable corrosion. Both the LDX 2101® and 2205p stainless steel bars exhibited moderate staining of the bars used as cathodes in oxygenated pore solution

Rapid Macrocell Tests of Enduramet® 2304 Stainless Steel Bars

The corrosion performance of epoxy-coated steel meeting the requirements of ASTM A775 with the coating in an undamaged condition and two damaged conditions (0.04% and 0.83% damaged area) is evaluated in accordance with Annexes A1 and A2 of ASTM 955 and compared with the corrosion performance of conventional reinforcing steel meeting the requirements of ASTM A615 steel and low-carbon, chromium steel meeting the requirements of A1035, with the latter in both the as-received and pickled conditions. Epoxy-coated bars provide significantly better corrosion performance than conventional reinforcing steel. The macrocell corrosion rates for bars with a damaged area equal to 0.04% of the area exposed to the solutions in the test are relatively low, and are, on average, similar to those observed for the undamaged epoxy-coated bars. Both undamaged and 0.04% damaged area epoxy-coated specimens meet the requirements for stainless steels specified in Annexes A1 and A2 of ASTM 955, with an average corrosion rate not exceeding 0.25 μm/yr and the corrosion rate of no individual specimen exceeding 0.50 μm/yr. The macrocell corrosion rates for bars with a damaged area equal to 0.83% of the area exposed to the solutions in the test average 1 to 1.5 μm/yr based on total bar area under the severe exposure conditions provided. Conventional and A1035 steel exhibit average values near 30 μm/yr for and 20 μm/yr, respectively. Pickling provides initial protection to A1035 steel bars, and to some bars for the duration of the test, but once corrosion initiates, corrosion appears to be similar to that observed on non-pickled bars

Rapid Macrocell Tests of ASTM A775, A615, and A1035 Reinforcing Bars

The corrosion performance of epoxy-coated steel meeting the requirements of ASTM A775 with the coating in an undamaged condition and two damaged conditions (0.04% and 0.83% damaged area) is evaluated in accordance with Annexes A1 and A2 of ASTM 955 and compared with the corrosion performance of conventional reinforcing steel meeting the requirements of ASTM A615 steel and low-carbon, chromium steel meeting the requirements of A1035, with the latter in both the as-received and pickled conditions. Epoxy-coated bars provide significantly better corrosion performance than conventional reinforcing steel. The macrocell corrosion rates for bars with a damaged area equal to 0.04% of the area exposed to the solutions in the test are relatively low, and are, on average, similar to those observed for the undamaged epoxy-coated bars. Both undamaged and 0.04% damaged area epoxy-coated specimens meet the requirements for stainless steels specified in Annexes A1 and A2 of ASTM 955, with an average corrosion rate not exceeding 0.25 μm/yr and the corrosion rate of no individual specimen exceeding 0.50 μm/yr. The macrocell corrosion rates for bars with a damaged area equal to 0.83% of the area exposed to the solutions in the test average 1 to 1.5 μm/yr based on total bar area under the severe exposure conditions provided. Conventional and A1035 steel exhibit average values near 30 μm/yr for and 20 μm/yr, respectively. Pickling provides initial protection to A1035 steel bars, and to some bars for the duration of the test, but once corrosion initiates, corrosion appears to be similar to that observed on non-pickled bars

On the origin of radial anisotropy near subduction slabs in the mid-mantle

Recent seismic studies indicate the presence of seismic anisotropy near subducted slabs in the transition zone and uppermost lower mantle (mid‐mantle). In this study, we investigate the origin of radial anisotropy in the mid‐mantle using 3‐D geodynamic subduction models combined with mantle fabric simulations. These calculations are compared with seismic tomography images to constrain the range of possible causes of the observed anisotropy. We consider three subduction scenarios: (i) slab stagnation at the bottom of the transition zone; (ii) slab trapped in the uppermost lower mantle; and (iii) slab penetration into the deep lower mantle. For each scenario, we consider a range of parameters, including several slip systems of bridgmanite and its grain‐boundary mobility. Modeling of lattice‐preferred orientation shows that the upper transition zone is characterized by fast‐SV radial anisotropy anomalies up to −1.5%. For the stagnating and trapped slab scenarios, the uppermost lower mantle is characterized by two fast‐SH radial anisotropy anomalies of ∼+2% beneath the slab's tip and hinge. On the other hand, the penetrating slab is associated with fast‐SH radial anisotropy anomalies of up to ∼+1.3% down to a depth of 2,000 km. Four possible easy slip systems of bridgmanite lead to a good consistency between the mantle modeling and the seismic tomography images: [100](010), [010](100), [001](100), and urn:x-wiley:ggge:media:ggge22043:ggge22043-math-0001. The anisotropy anomalies obtained from shape‐preferred orientation calculations do not fit seismic tomography images in the mid‐mantle as well as lattice‐preferred orientation calculations, especially for slabs penetrating into the deep lower mantle

Perspective and priorities for improvement of parathyroid hormone (PTH) measurement – A view from the IFCC Working Group for PTH

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described