Paula López

Thermal infrared identification of buried landmines

This paper deals with a three-dimensional thermal model for landmine detection problems and an inverse problem for reconstructing the physical parameters of buried objects. Moreover, solutions are given for the estimation of the soil thermal diffusivity and meteorological parameters, needed for solving the inverse problem. The paper describes the main fundamental principles of thermal modelling for buried object identification and illustrates the results on data acquired from a real minefield, together with qualitative and quantitative results illustrating the validity of the model.

CNN-based 3D thermal modeling of the soil for antipersonnel mine detection

The inherent analogies between the defining equation of CNN and that of heat transfer are well known. In this paper, we explore the projection of a 3D thermal model of the soil on this kind of structure. In so doing, reliable and fast prediction of the thermodynamic behavior of soil subject to known boundary conditions can be obtained. That way, it is possible to characterize different kinds of soil in terms of its thermal signature. Based on that knowledge, and using an inverse approach, we perform the detection of buried land mines.

Design and training of multilayer discrete time cellular neural networks for antipersonnel mine detection using genetic algorithms

In this work we present a novel strategy for the simultaneous design and training of multilayer discrete-time cellular neural networks. This methodology is applied to the detection of surface-laid antipersonnel mines in infrared imaging. The procedure is based on the application of genetic algorithms for both network design and learning task.

Performance analysis of high-speed MOS transistors with different layout styles

Several layout schemes for MOS transistors have been investigated and compared in terms of speed and layout area. Among them, the so-called closed, donut or doughnut transistors have been characterized, obtaining an analytical expression for the calculation of the equivalent W/L ratio for a general n-side regular polygonal-shape. The comparisons show that with quasi-minimum dimension transistors and L=0.35 /spl mu/m, reductions of up to 81% on the drain area can be achieved with an increase of only a 10% on the total layout area for given W and L. An application improving the switching speed of an output multiplexer is shown.

A Verilog-AMS photodiode model including lateral effects

The market of CMOS image sensors is rapidly gaining an importance since optoelectronic devices are present in an increasing number of electronic systems. Therefore, accurate scalable optoelectronic models for photodetectors are necessary to predict their behaviour by circuit simulation. Hardware description languages (HDLs) offer an effective and efficient way to describe these systems. In this work, a Verilog-AMS model for the photoresponse of a CMOS photodiode including lateral effects is presented and a simplified equivalent electrical circuit of the photodiode is used to simulate two different pixel cells in Cadence framework.

Detection of perturbations in thermal IR signatures: an inverse problem for buried land mine detection

The analysis of pertrubations on the thermal signature of the soil is a powerful tool for the detection of the presence of buried objects on the soil from measured infrared images but, by itself, gives litle insight in the nature of the detected targets. In this paper, we will present a method for the detection of surface and shallowly buried land mines in infrared images based on a 3D thermal model of the soil. This model will be used to detect perturbations on the expected behavior that will lead to the assumption of the presence of unknown buried objects. Next, we will outline a procedure that makes use of the theory on inverse problems in order to extract information of the natuer of the detected targets and to infer whether they actually correspond to land mines or not.

Distance Measurement Error in Time-of-Flight Sensors Due to Shot Noise

Unlike other noise sources, which can be reduced or eliminated by different signal processing techniques, shot noise is an ever-present noise component in any imaging system. In this paper, we present an in-depth study of the impact of shot noise on time-of-flight sensors in terms of the error introduced in the distance estimation. The paper addresses the effect of parameters, such as the size of the photosensor, the background and signal power or the integration time, and the resulting design trade-offs. The study is demonstrated with different numerical examples, which show that, in general, the phase shift determination technique with two background measurements approach is the most suitable for pixel arrays of large resolution.

Wireless sensor mote for snail pest detection

The novelty of this contribution is a custom-made system for snail pest detection that comprises: a shelter to trap snails, a custom photoelectric sensor to detect the snail, a battery and solar cell to power the system, and an Arduino FIO with Xbee to run the Zig-Bee protocol for communication purposes. The ultimate goal is the deployment of a wireless sensor network (WSN) for early snail pest detection to minimize the use of pesticides in crops. Although this is not the first paper on pest detection with WSNs, every pest and scenario needs a specific sensor. In particular, the shape of the shelter discards commercial photoelectric sensors. Also, cost and power consumption lead to the design of a specific conditioning circuitry and strategies to save energy in conjunction with a solar cell to recharge a 1000 mA·h LiPo battery. The battery alone would power the system for 164 days.

Experimental characterization of peripheral photocurrent in CMOS photodiodes down to 65?nm technology

In this work, an in-depth experimental characterization of submicron CMOS p–n+ junction photodiodes operating under uniform illumination in the visible range is performed. The experimental measurements are used to validate a previous two-dimensional analytical model for the photoresponse estimation of these structures, which pays special attention to the lateral collection and was verified by means of device simulations. To do so, square p–n+ junction photodiodes with different sizes down to an active area of 0.56 μm wide have been fabricated in 180 and 65 nm technological nodes and characterized under blue, green and red light sources. As a result, the importance of the lateral collection in the overall response for small photodiodes that was previously theoretically reported is confirmed. The experimentally validated two-dimensional analytical model is a powerful tool that can be employed for the design of CMOS imagers and related electronics circuits.

Improved Analytical I-V model for polygonal-shape enclosed layout transistors

An improved analytical I-V model accounting for the influence of short-channel effects on radiation-tolerant doughnut transistors is presented. The model is validated using TCAD simulation of the devices. The impact of this layout style on the driving capability of the devices is also analyzed confirming that it is seriously compromised in the case of large channel transistors which, together with an increase in the layout area discourages its use. However, for short-channel devices the driving capability is improved.