Forecasting Engineering Team Capacity and Work Estimates Using Product Roadmaps

Despite substantial research, deriving work estimates and team capacity for a given software development project continues to be notoriously difficult to get right. This disclosure describes techniques to automatically and rapidly calculate, in the same unit of measure, engineering team capacity and engineering work estimates for a given set of product features. With use of the described techniques, software development projects can be better organized, and engineering talent can spend time on engineering problems rather than on planning. The automated team capacity and work estimate calculations can be more accurate than typical human-generated estimates, and lead to more accurate product development decisions. Planning data across the development organization is standardized into a common data model to support deeper analysis. Historic team capacity and work estimate data is leveraged to accurately and automatically predict future work and resource estimates using heuristic and statistical techniques. Automated, tailored communication including structured planning data, actions, and insights is delivered to responsible individuals or groups in a timely manner

Effect of thermal annealing on dielectric and ferroelectric properties of aerosol-deposited 0.65Pb(Mg1/3Nb2/3)O3−0.35PbTiO30.65\text{Pb}(\text{Mg}_{1/3}\text{Nb}_{2/3})\text{O}_{3}-0.35\text{PbTiO}_{3} thick films

In this work, the effects of thermal annealing at 500 {\deg}C on aerosol-deposited $0.65\text{Pb}(\text{Mg}_{1/3}\text{Nb}_{2/3})\text{O}_{3}-0.35\text{PbTiO}_{3}$ thick films on stainless-steel substrates are investigated using two complementary methods at high and low applied external electric fields. The first one is Positive Up Negative Down method, which allows us to obtain information about the switching and non-switching contributions to the polarization. It shows that the as-deposited film is ferroelectric before annealing, since it has a switching contribution to the polarization. After annealing, both the switching and non-switching contributions to polarization increased by a factor of 1.6 and 2.33, respectively, indicating stronger ferroelectric behavior. The second method is based on impedance spectroscopy coupled with Rayleigh analysis. The results show that post-deposition thermal annealing increases the reversible domain wall contribution to the dielectric permittivity by a factor 11 while keeping the threshold field similar. This indicates, after annealing, domain wall density is larger while domain wall mobility remains similar. These two complementary characterization methods show that annealing increases the ferroelectric behavior of the thick film by increasing the domain wall density and its influence is visible both on polarization versus electric field loop and dielectric permittivity

Fabrication and modeling of piezoelectric transducers for High-Frequency medical imaging

International audienceWe have studied the processing of piezoelectric thick films using electrophoretic deposition (EPD) for high-frequency ultrasound applications. Lead-zirconium-titanate (PZT) particles synthetized by solid states synthesis were dispersed in ethanol using ammonium polyacrylate (PAA). The electrophoretic deposition of PZT particles was performed at a constant-current mode. PZT thick-films deposited at 1 mA for 60 seconds were sintered at 900oC for 2 hours in a PbO-controlled atmosphere. The scanning-electron microscopy (SEM) analysis shows that the thickness of PZT layer is uniform and that the pores are homogeneously distributed within the layer. The complex electrical impedance was measured and fitted by KLM scheme in order to deduce the dielectric, mechanical and piezoelectric parameters of the thick-films. The density and thickness of PZT thick films are used as inputs and the thickness coupling factor kt, dielectric constant at constant strain and resonant frequency are deduced. The results show that homogeneous PZT thick-film structures with tailored thickness and density prepared by EPD and sintering having a resonant frequency around 20 MHz can be used for noninvasive medical ultrasound imaging and diagnostics

Ultrasonic transducers based on curved lead-free piezoelectric thick films for high resolution medical imaging

International audienceKNN-based lead free ferroelectric materials are receiving much attention due to their high electromechanical properties that make them promising candidates to replace the lead-based piezoceramics that will eventually be banned by environmental regulations in many countries over the world. Studies include the development of KNN thick films that are particularly well adapted for high frequency applications due to higher wave velocities and a dielectric constant in an acceptable range for single element transducers. Here, a KNN based thick film is deposited on a curved substrate by pad-printing in order to be used in a focused high frequency transducer. This substrate is a porous lead-free KNN cylinder specifically developed to exhibit the required acoustical properties of a backing (acoustical impedance, high attenuation) and is compatible with the high sintering temperature of the KNN thick film. Electromechanical properties of the piezoelectric thick film in thickness mode were deduced (kt over 35%). This structure was used to fabricate a transducer which was characterized (relative bandwidth over 90%). Finally this transducer was integrated in a high frequency imaging system and its performance allowed skin images to be produced. To conclude, the replacement of lead-based high frequency transducers by green devices is a viable option

Non-Planar Pad-Printed Think-Film Focused High-Frequency Ultrasonic Transducers for Imaging and Therapeutic Applications

Pad-printed thick-film transducers have been shown to be an interesting alternative to lapped bulk piezoceramics, because the film is deposited with the required thickness, size, and geometry, thus avoiding any subsequent machining to achieve geometrical focusing. Their electromechanical properties are close to those of bulk ceramics with similar composition despite having a higher porosity. In this paper, padprinted high-frequency transducers based on a low-loss piezoceramic composition are designed and fabricated. High-porosity ceramic cylinders with a spherical top surface are used as the backing substrate. The transducers are characterized in view of imaging applications and their imaging capabilities are evaluated with phantoms containing spherical inclusions and in different biological tissues. In addition, the transducers are evaluated for their capability to produce high-acoustic intensities at frequencies around 20 MHz. High-intensity measurements, obtained with a calibrated hydrophone, show that transducer performance is promising for applications that would require the same device to be used for imaging and for therapy. Nevertheless, the transducer design can be improved, and simulation studies are performed to find a better compromise between low-power and high-power performance. The size, geometry, and constitutive materials of optimized configurations are proposed and their feasibility is discussed

Multifunctional energy storage and piezoelectric properties of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 thick films on stainless-steel substrates

AbstractThe miniaturization of electronic devices and power systems requires the fabrication of functional components in the form of micrometer-sized thick films. A major challenge is the integration of functional ceramics with metals, which are considered incompatible with high-temperature ceramic processing. To overcome the integration barrier, an aerosol deposition (AD) spray-coating method based on room temperature deposition can be used. By employing the AD method, we were able to deposit relaxor-ferroelectric 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 ceramic thick films on low-cost stainless-steel substrates. The as-deposited films were dense, with ∼97% of the theoretical density. Moreover, the post-deposition annealing at 500 °C did not result in any microstructural changes. Compared to the as-deposited films, the annealed films exhibit improved energy storage and electromechanical properties. The annealed thick films achieve a recoverable energy density of 15.1 J⋅cm−3 at an electric field of 1350 kV⋅cm−1 and an electric-field cycling stability of 5 million cycles. A piezoelectric response was detected through the entire film thickness by piezoelectric force microscopy. Macroscopic displacement measurements revealed a maximum relative strain of 0.38% at 1000 kV⋅cm−1, corresponding to inverse effective piezoelectric coefficient of ∼40 pm⋅V−1. In this study, we overcame the integration challenges and demonstrated the multifunctionalization of future ceramic-metal structures, as the deposited thick films on stainless steel exhibit energy storage capability and piezoelectric properties

1-3-Type Composites Based on Ferroelectrics:Electromechanical Coupling, Figures of Merit, and Piezotechnical Energy-Harvesting Applications

The physical and microgeometric factors that are able to improve the piezoelectric performance, anisotropy, and energy-harvesting characteristics of modern 1-3-type composites based on ferroelectrics are discussed. The composite connectivity patterns of particular interest for this study include 1-3-0, 1-0-3, and 1-2-2. The active components of the studied composites are chosen from conventional perovskite-type ferroelectric ceramics, lead-free materials, or domain-engineered single crystals, all of which exhibit particularly intriguing electromechanical properties. Examples of the large anisotropy of piezoelectric coefficients, electromechanical coupling factors, squared figures of merit, and large hydrostatic parameters of the three-component 1-3-type composites are considered in the context of their piezotechnical applications. The applications of these materials include piezoelectric transducers, sensors, energy-harvesting, and hydroacoustic devices.</p

Theoretical Study on the Piezoelectric Performance of Lead-Free 1–3-Type Composites

The paper is devoted to the analysis of high-performance piezo-composites based on lead-free ferroelectric single crystals. The composite consists of parallelepiped-shaped single-crystal rods which are surrounded by a laminar polymer matrix, and the composite as a whole is described by 1–2–2 connectivity. Such a composite structure promotes high piezoelectric sensitivity and hydrostatic response. Of particular interest are piezoelectric coefficients g*33 and h*33, squared figure of merit d*33 g*33, electromechanical coupling factor k*t at the thickness-mode oscillation, and hydrostatic parameters g*h and d*h g*h. The influence of the laminar matrix on the aforementioned parameters is studied in a wide volume-fraction range. Examples of maxima and large anisotropy of some effective parameters are discussed for the 1–2–2 composites based on [Lix(K1−yNay)1−x](Nb1−zTaz)O3:Mn single crystals. The role of elastic properties of the laminar matrix in achieving large hydrostatic parameters and piezoelectric anisotropy of these composites is emphasised. Their effective parameters are compared to those of composites based on the lead-containing relaxor-ferroelectric single crystals and to specific parameters of poled textured ceramics. Advantages of the studied composites over the relaxor-ferroelectric-based composites and textured ceramics open up new possibilities to apply the 1–3-type lead-free composites as active elements of piezoelectric sensors, hydrophones, energy-harvesting, and transducer devices.</p