Hot deformation of spray formed nickel-base superalloy using processing maps

The hot compression testing of hot isostatically pressed(HIPed) spray formed(SF) nickel-base superalloy was carried out by thermal mechanical simulator in the temperature range of 1 050-1 140 ℃ at strain rates of 0.01-10 s-1 and engineering strain of 50%. A processing map was developed on the basis of these data by using the principles of dynamic materials modeling. The microstructural evolution of deformed samples was also examined on the basis of optical and electron microscopic observations. The map exhibits two domains: the instability domain at the temperatures of 1 050 ℃ -1 110 ℃ and strain rate of 0.01 s-1, the stability domain at the temperatures of 1 110 ℃- 1 140 ℃ and strain rates of 1 s-1-10 s-1, with a peak efficiency of about 40%. The dynamic recrystallization(DRX) is observed in the stability domain and the deformed specimens are no cracking or instabilities. However, there is no DRX in the instability domain and the alloy exhibits flow instability with cracks due to poor workability. The optimum hot working condition was determined in the stability domain.

Diameters and form of skull base foramen ovale measured by three-dimensional spiral CT thin-slice scan in healthy adults

BACKGROUND： The accurate measurements of various data of the bone diameters of foramen ovale of living person can change the methods of puncturing trigeminal gasserian ganglion via foramen ovale for treating trifacial neuralgia from the experience of puncture operator only to puncture by taking the objective data of measurement as the evidence, which is good for improving the accuracy of puncturing trigeminal ganglion and reducing side effects. OBJECTIVE ： To observe the forms of foramen ovales in healthy adults displayed by volume rendering and multi-planar reconstruction after three-dimensional spiral CT thin-slice scan of skull base, and measure the longitudinal diameter and transverse diameter. DESIGN ： A repetitive observation and measurement SETTINGS ： Department of Neurosurgery and Department of Medical Imaging, Foshan Hospital of Traditional Chinese Medicine. PARTICIPANTS： Fifty healthy adults （100 sides）, who were examined with three-dimensional spiral CT scan, were randomly selected from the Department of Medical Imaging, Foshan Hospital of Traditional Chinese Medicine from January 2005 to January 2006, including 26 males and 24 females, aged 25-68 years with an average of 48 years old. They were all informed and agreed with the examination. METHODS ： The subjects were examined with the Philips 16-slice spiral CT-Mx 8000 IDT CT apparatus （Philips Company, Holland）, the scanning ranged from 2 cm below the canthomeatal line to the level of suprasellar cistem. The width of collimator was 0.75 mm, pitch was 0.663; tube current was 350 mA, voltage was 120 kV, resolution was 512×512 matrix; slice thickness of reconstruction was 1 mm, and interval was 0.5 mm. After the three-dimensional spiral CT thin-slice scan of skull base, the image post-processing techniques including volume rendering and multi-planar reconstruction were applied to observe the forms of foramen ovales, and measure the size, longitudinal diameter and transverse diameter of the foramen ovales. The figures of the foramen ovales were drawn with mouse along the boundary of bone porous margin and soft tissue. According to the indications, the diameters were measured with computer to observe the forms of foramen ovales. MAIN OUTCOME MEASURES ： The longitudinal diameter, transverse diameter and form of foramen ovales were observed. RESULTS： All the 50 healthy adults （100 sides） were involved in the analysis of results. （1） It was observed in the volume rendering images that foramen ovales had four forms of oval shape （77 sides）, kidney shape （12 sides）, round shape （7 sides）, ribbon shape （4 sides）. （2） The longitudinal diameters of left and right foramen ovales were （7.67±1.32） and （7.98±1.45） mm, and the transverse diameters were （4.04±0.83）, （4.09±1.07） mm; There was no obvious difference between left and right longitudinal diameters （t = 1.63, P = 0.11 ）, and left and right transverse diameters were close （t = 0.45, P= 0.65）. CONCLUSION ： The non-invasive techniques of volume rendering and multi-planar reconstruction after three-dimensional spiral CT thin-slice scan can clearly display the formand size of foramen ovale in healthy adults.

VISION-BASED MEASUREMENT OF FREE-FORM SURFACES

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Effect of Sr on forming properties of Al-Mg-Si based alloy sheets

The effects of Sr element on the forming properties of the Al-Mg-Si based alloy sheets were studied by tensile test, metallograph, DSC, XRD, SEM and TEM. The results show that the tensile strength of aluminum alloy sheet added 0.033%(mass fraction)Sr increases comparing with that of free Sr. Simultaneously, the forming properties of sheets evidently increase, the elongation hardenability (n) and plastic strain ratio (r) and Erichsen number increase 27.8%, 11.1%, 10.8% and 12%, respectively, and the forming limit diagram increases evidently, too. The analysis shows that Sr is surface active element, which can refine grains of alloys, promote precipitation, reduce activation energy ofβ' phase, and lead the formation ofα-(Al8Fe2Si) phase instead ofβ-(Al5FeSi) phase. As a result, the forming properties of the alloy sheet increase.

Effect of Ni on glass-forming ability of Cu-Ti-based amorphous alloys

Ribbons of amorphous Cu-Ti-Ni alloys were prepared by the melt spinning method. The amorphous structure of these ribbons was confirmed by X-ray diffractametry and transmission electron microscopy. The effect of Ni on the glass-forming ability of Cu-Ti-based alloys was studied by differential scanning calorimetry(DSC). It is found that the supercooled liquid region, ?Tx value shows the maximum value of 61℃ at x=10 in the Cu50Ti50?xNix (x=0, 5, 10, 15 mole fraction, %) system. And the reduced glass transition temperature, Trg, is smaller than 0.45. The glass forming ability(GFA) of Cu-Ti alloy is not effectively promoted by Ni addition.

Abnormal mechanical property evolution induced by heat treatment for a semi-solid forming hypereutectic Al-Fe base alloy

In the present study, Al-5.5Fe-4Cu-2Zn-0.4Mg-0.5Mn al oy samples were prepared by electromagnetic stirring and semi-solid forming processing, and then the effects of T6 and T1 heat treatments on the microstructures and mechanical properties of the semi-solid forming samples were investigated. The results indicate that after semi-solid forming, the mechanical properties of the sample improved significantly compared to that of the merely electromagnetically stirred sample. The grains of semi-solid forming alloy became almost fine equiaxed; big long strip-shaped Al3 Fe phases became short rod-like morphology and distributed uniformly in the matrix. However, the mechanical properties of the T6-treated semi-solid forming sample decreased significantly instead of increasing and, with solution temperature rising, the tensile strength of the al oy decreased further. The results of EDS show that after high temperature solid-solution treatment, the Cu element in the semi-solid forming alloy sample is mainly concentrated at the boundaries of the Al3 Fe phases instead of being dissolved in the matrix. At the same time, the grains of the semi-solid forming sample grew slightly after solid-solution treatment. Therefore, the growth of the grains and the accumulation of Cu element at Al3 Fe phase boundaries during solution treatment of the semi-solid forming alloy were the main reasons for the mechanical properties decreasing after T6 treatment. The mechanical properties of the alloy were improved after T1 heat treatment due to aging strengthening phase being precipitated in the matrix.

Acceptability of Phone-Based Communication Intervention by Healthcare Workers as an Adjunct to Routine Referral Form: A Qualitative Study in South Western Uganda

Introduction: A functional maternal referral system should encompass a feasible communication system between health facilities. In Uganda, the current paper-based patient referral form is associated with inadequate patient-information and low feedback rates. A recent quasi-experimental study demonstrated that a phone-based communication intervention is feasible for iterative communication between health facilities, and there were improved maternal-fetal outcomes and high rates of feedback. However, the acceptability of the intervention was not assessed. Objective: The study assessed the acceptability of a phone-based communication intervention by the health care workers (HCWs) for iterative communication between the referring and receiving health facilities. Methods: This was a qualitative study conducted in South Western Uganda, in April 2021. The study employed a theoretical framework of acceptability of medical interventions. We conducted in-depth interviews with HCWs and used deductive-inductive analysis. Results: We enrolled a total of 23 HCWs, of whom 69.6% (n = 16) were females while 30.4% (n = 7) were males. Majority (65.2%, n = 15), were midwives and the rest were: doctors (30.4%, n = 7) and a nurse (4.3%). The HCWs were positive towards the intervention: they believed that the intervention reduced delays, promoted professional escort, encouraged sharing of supplies, enabled exchange of relatively more patient details, feedback and improved case management. They believed it was culturally acceptable and had enough skills and experience of operating phones. All participants recommended scale out of the intervention, but advised on the need for dedicated human-resource to coordinate phone calls, ensure availability of airtime and charged battery. Conclusion: This study demonstrates that the phone-based communication intervention was highly accepted by the healthcare workers, and that hospitals can successfully give feedback to lower health centres through iterative phone calls. This provides a possible solution to the long-standing challenge of poor feedback rates and a vicious cycle of poor maternal-fetal outcomes in resource limited settings.

ANALYSIS OF TOOTH FORM ERROR OF EQUAL BASE CIRCLE BEVEL GEAR

The basic principle of equal base circle bevel gear (EBCBG) is illustrated simply Thetooth surface equation of EBCBG manufactured by end milling cutter with involute profile is de-rived. The tooth form error is analyzed on the basis of spherical involute

Humanoid Based Intelligence Control Strategy of Plastic Cement Die Press Work-Piece Forming Process for Polymer Plastics

The plastic cement belongs to a sort of polymer material, the chemical composition is very complex, and the plastic cement work-piece is generally manufactured by die press forming. Aimed at being difficult to control in parameters of forming process, the paper explored the humanoid based intelligence control strategy. In the paper, it made the anatomy in control puzzle resulted in uncertainty such as chemical component of plastic cement etc., summarized up the characteristic of cybernetics in forming process, researched on the humanoid based intelligence control strategy, and constructed the control algorithm of forming process in plastic cement work-piece. Taking the process experiment of temperature and pressure control as an example, it validated the good dynamic and static control quality through simulation of control algorithm constructed in this paper. The experimental results show that the control algorithm explored in this paper is reasonably available.

Dual Focus on Form and Meaning in Task-based Oral English Teaching

The task-based approach has been gaining more and more popularity in recent years. Unlike the traditional language teaching approach, which puts much emphasis on the teaching and learning of language forms and skills, it regards the language process as one of learning through doing, emphasizes the central role of meaning in language use and insists that students should learn more effectively if they are fully engaged in a language task. However, due to the lack of an appropriate language environment and limited time for English study, Chinese students may not make as much progress as expected in the unconscious internalization of authentic language by focusing primarily on meaning. In fact the meaning of a language can not be separated from its form. The accurate expression of meaning depends on the proper use of language form. Therefore, in the application of the taskbased approach, we should not neglect the study of language form. This paper analyses the causes for Chinese students' low spoken English proficiency, describes the theoretical foundation and actual practice of the task-based approach, discusses its implications for teaching oral English and makes some proposals for its appropriate application.

An Initial Plan to Explore the Use of CALL in Task-Based Instruction in College English Writing in China

Learning for using theories has been,to a great degree,acceptable over the last few decades.Learning through doing,through using the language,through performing real life or real-life-like tasks has come to its own important occasions to achieve EFL/ESL learners' communicative goals.

XBase系统下的数据文件格式的比较与研究

本文介绍了Xbase系列数据库管理系统尤其Fox和VFP数据文件的差异 ,分析了VFP下的数据文件 ,结果表明系统对项目文件、数据库、表的管理均为二维表方式 ,在此基础上进一步分析研究了Fox与VFP数据文件的存储格式 ,对其在物理结构上的差异作了更为详尽地阐述。

Continuously extending extrusion forming of semisolid A2017 alloy by SRS process

A self-made single-roll stirring (SRS) machine was used to manufacturesemisolid A2017 alloy, the mechanism of A2017 alloy formation was investigated. It was shown thatA2017 dendrites growing on the rough roll surface are crashed into fragments by the roll, which moveand grow freely then contribute the formation of finer spherical microstruc-ture. When casting at710-750℃, fine and homogeneous spherical or elliptical grains of A2017 alloy were obtained.Extending forming mould has been designed and was installed at the exit of roll-shoe gap. A2017alloy was formed by extending continuously at the semisolid state on SRS machine. Throughcontrolling pouring temperature, semisolid forming and extending extrusion was combined organically.A2017 product with fine surface and rectangular transection of 14 mm x 25 mm was obtained. Bycontrast to the national standard, the fracture strength and elongation of A2017 products producedfrom extending semisolid extrusion have been improved with an increase of 100 MPa and 29%,respectively.

Glass-forming ability and crystallization of Mg-Ni amorphous alloys with Y addition

Mg86.33Ni13.67-xYx(x=0, 1, 3, 6, 10) amorphous alloys were obtained by single-roller melt-spinning technique and the effect of Y addition on the glass forming ability(GFA), crystallization and micro-hardness of Mg-Ni alloys were studied. The results show that the GFA of Mg86.33Ni13.67-xYx(x=0, 1, 3, 6, 10) is improved successfully with the Y addition. The highest GFA appeares at x=6, while the reduced glass transition temperature (Trg) is 0.5225 and the supercooled liquid region(ΔTx) is 42.06 K; the position of the main diffraction halo is different for the alloys, and the maximum of the main diffraction halo of alloys with x=0, 1, 3 corresponds to the main peaks of a metastable fcc-Mg6Ni or fcc-Mg6Ni + Ni-Y intermetallic phases, and for the alloys with x=6, 10, it corresponds to Mg-Y and Ni-Y intermetallic phases; the micro-hardness of the alloys is improved with Y additions, and the highest micro-hardness is obtained at x=6 at.%, which is 960 MPa.

Microstructural evolution and characteristics during sintering of submicron Ti(C,N)-based cermet

Ti（C,N）-based cermets were prepared with submicron powders. The microstructure evolution and characteristics during the sintering of cermet were studied by TEM, SEM, EDX and XRD. The forming mechanism of the structures was also studied. There exist inner rim and outer rim between the hard cores and the binder. The inner rim is enriched in Mo and W compared with the outer rim, and is formed during the solid sintering by counter diffusion of TiC, Mo2C and WC. The outer rim is formed during the liquid sintering by Ostwald ripening mechanism.

Formation and Mechanical Properties of Zr-Nb-Cu-Ni-Al-Lu Bulk Glassy Alloys with Superior Glass-Forming Ability

Glass-forming ability（GFA） and mechanical properties of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x= 0-3 at%） alloys have been investigated.The GFA of Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is dramatically enhanced by adding Lu.The（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy possesses the highest GFA in the studied Zr-Nb-Cu-Ni-Al-Lu alloys,with its critical diameter for glass formation reaching 20 mm by copper-mould casting method,while that of the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is 7 mm.The critical diameters of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x =1 at%and 3 at%） alloys are 15 mm and 12 mm,respectively.The Lu addition to Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy induces the change of initial crystallization phases from face-centred-cubic Zr_2Ni and tetragonal Zr_2Ni phases for the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy to an icosahedral quasi-crystalline phase for the Lu-doped alloys,which may be the origin for the enhanced GFA of the Lu-doped alloys.The compressive fracture strength and plastic strain of the bulk glassy（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy are1 610 MPa and 1.5%,respectively.

Dependence of Amorphous Formation Ability on Intrinsic Parameters in Dy-Gd-Co-Al Alloys

A series of Dy（Gd）-based bulk amorphous alloy rods were prepared by water-cooled copper mold method. Thermal stability and structure of Dy-Gd-Co-Al alloys were investigated by differential scanning calorimetry and X-ray diffraction, respectively. The results show that the Dy-Gd-Co-Al alloys have good glass-formation ability, and the Dy31Gd25Co20Al24 alloy can be readily cast into full glassy rods up to 5 mm in diameter. The glass-forming ability of multicomponent alloys was greatly dependent on their chemical interaction and the equivalent bond parameters among atoms such as equivalent electronegativity difference, equivalent atomic size parameter. The Dy （Gd）-based bulk amorphous alloys could be expected as potential functional materials.

Effect of addition of Zn and Al elements on glass-forming ability and thermal stability of Mg-Cu-Y bulk metallic glasses

After substituting partial Cu and Mg with Zn or Al elements for Mg65Cu25Y10 alloy,respectively,the metallic glass plate samples with thickness of 2-3 mm were prepared by water-quenching,their respective glass-forming ability and thermal stability were studied by using differential thermal analysis(DTA) and X-ray diffraction(XRD). Using Kissinger equation,the activation energies of crystallization of these metallic glasses heated with a constant rate were calculated. The results show that Al element is greatly harmful to the glass-forming ability of Mg-Cu-Y alloys and cannot acquire bulk amorphous alloys;nevertheless,the effect of Zn element addition is indeterminate for various components. The magnitudes of thermal stability are also revealed.