Revista Militar de Ciência e Tecnologia

Edição Completa Impressa

2023-12-04T11:21:43+00:00

EDITORIAL E SUMÁRIO

2023-12-04T11:19:58+00:00

Português

2023-09-21T14:50:27+00:00

In the context of road enforcement, automated electronic equipment are capable of reading the characteristics of passing vehicles, including their identification, measurements, speed or weight. Although such equipment can be used to create monitoring and enforcement networks, drivers can, in many contexts, plan their routes in order to avoid passing through enforcement systems, knowing their location. Flows that may exhibit such evasive tendencies are, for example, vehicles intentionally overloaded, stolen or carrying out other illegal activities. The negative impact of these flows can be minimized by using equipment location models that consider the driver’s evasive behavior. This article presents a systematic review of existing location methods in the literature for intercepting flows with evasive behavior. The formulation of the Evasive Flow Capture Problem (EFCP) is highlighted, and some alternative algorithms applicable in Brazilian road networks are presented, including a case study.

Proposal of optimization models for movements of Brazilian Army military personnel

2023-09-21T14:50:27+00:00

The permanent change of station (PCS) of the Brazilian Army military among the various Military Organizations (OM), these grouped in the so-called garrisons in several cities, is an activity carried out annually by the Directorate of Personnel and Movement Control (DCEM), which aims to meet, in the best possible way, the needs of the Force and the interests of the military. To optimize the relocations of the military, this article presents the development of a mathematical model, based on a problem of resource allocation, and compares his results with those presented by the Decision Support System for Movements (SADMov), currently in use, which is based on a constructive algorithm. Computer experiments were carried out for a sample of 277 lieutenants of the Infantry, 374 garrisons and 912 military organizations. The results of optimizations indicate a positive attendance of 121% for the military and 34% for the OM.

Avaliação dos principais modelos de admitância da sonda coaxial aberta para medidas de permissividade elétrica

2023-09-21T14:50:27+00:00

The accurate knowledge of the dielectric properties of
materials, especially permittivity, is essential in several areas of
engineering. The present work deals with the reflective method of
dielectric characterization based on coaxial sensors. It presents an
evaluation of various admittance models available in the literature
for the sensor and a comparison between them, attempting to
identify a fast and accurate model for practical applications. In this
context, the two inherent problems to the coaxial probe method are
addressed, one related to the admittance determination as a
function of permittivity (direct problem) and another related to the
permittivity determination as a function of admittance (reverse
problem). In the present work, the solutions of the direct problem
available in the literature are addressed.

Escória de aciaria como material precursor na geopolimerização

2023-09-21T14:50:27+00:00

ABSTRACT: Geopolymer materials are progressively studied due to their good properties that can even be compared to Portland cement concrete. For geopolymerization, a precursor material is required, which is rich in alumina (Al₂O₃) and silica (SiO₂). Ladle furnace slag is an industrial waste that suits the needs of geopolymer synthesis. This study analyzes the geopolymerization performed with ladle furnace slag through X-ray diffraction (XRD); Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. With the XRD analysis, it was possible to identify crystalline phases and some peaks characteristic of geopolymerization; in the FTIR spectroscopy, the displacement of some bands by the incorporation of aluminum and in SEM images, the difference in morphology between pure slag and geopolymer, confirming the occurrence of geopolymerization.

Influência da adição de carbeto de titânio na densificação e microestrutura de cerâmicas de alumina dopadas com nióbia e fluoreto de lítio

2023-09-21T14:50:27+00:00

Ceramic matrix composites are objects of study in the ballistic sector due to the high hardness associated with fracture toughness and improved ballistic performance in multilayer shielding systems. Ceramics without the presence of dopants make processing difficult and may compromise the final properties of the sintered material. This work aimed at the ceramic processing of ceramic matrix composites based on Al₂O₃, with additions of 4 w% of Nb₂O₅, 0.5 w% of LiF and 38.5 w% of TiC, processed by conventional sintering at 1400 °C/1h. Ceramics without the presence of TiC showed high densification values, whereas samples with TiC additions had severe reductions in their densification, becoming an extremely fragile and brittle material.

The influence of the maturation state of components on their approval in new product projects in the automotive industry

2023-09-21T14:50:27+00:00

The focus of the work is on the industrialization phase of externally purchased parts – tooling, development and construction of manufacturing methods and associated controls. The component/part development is done by the engineering of the organization: drawings / 3D CAD files / standards. The organization's purchasing department selects suppliers for the project – through the RFQ / Request for Quotation. Delay in component maturation (deviations from specification) and / or delay in supply can result in downstream delays, affecting both organization and customer. Also, performance issues in component / products. The literature that deals with the industrialization phase is very scarce and there are no records of an unsuccessful industrialization phase, or cases of success, for possible benchmarking between organizations.

Evaluation of agronomic variables and Sentinel-2 satellite images for sugarcane yield estimation using the Random Forest algorithm

2023-09-21T14:50:28+00:00

The objective of this project was to evaluate the importance of agronomic variables and Sentinel-2 satellite images to estimate sugarcane yield using the Random Forest algorithm. We used agronomic data referring to the variety, cutting stage, soil type and relief, in addition to data from satellite images referring to the average, maximum NDVI and the standard deviation of the NDVI of each field. Two empirical models were created considering: i) Agronomic variables, ii) Agronomic variables and Sentinel-2 images. The model to estimate sugarcane yield showed R² equal to 0.64 and 0.83, RMSE of 10.17 and 7.0 ton/ha for models i and ii, respectively. The evaluation of the importance of the variables indicated that the variable cutting stage was the most important, followed by the variables variety and average NDVI of the field. The combination of agronomic variables and satellite images brought improvements to estimate sugarcane productivity.

Microstructural characterization of sodium niobates by the sol-gel process for use in tissue engineering

2023-09-21T14:50:28+00:00

Sodium niobate is a potentially important dielectric material for its piezoelectric properties. It has a perovskite-like structure, in its most stable form. Recent advances in tissue engineering have focused on the use of biochemical and physicochemical signals to trigger specific cellular responses and encourage better biological interaction between the biomaterial and living tissue. Piezoelectric ceramics may be the key to the functionalization of current grafts, as they exhibit mechanically generated electrical behavior. In this work, the production of sodium niobate (NaNbO3), a piezoelectric biomaterial, in different molar compositions, by the sol-gel method was adopted in order to observe the changes in the microstructure using scanning electron microscopy (SEM) techniques. The synthesis was efficient, and the microstructure is in agreement with what was found in the literature.

Proposed methodology for temporal evaluation of leveling network bench marks using the Graph Theory

2023-09-21T14:50:28+00:00

The remeasurement of height diferences of the sections through the geometric leveling technique is na everyday activity in leveling networks. It generates many observations of the same section. This set of observations needs to be checked for consistency to minimize possible outliers’ insertion into the data. This work proposes, for the temporal evaluation of the leveling data, a methodology that: optimizes the usual method of analysis: explores alternatives when it cannot be applied taking advantage of available information; additionally it aims to make the assessment more homogeneous and non-subjective. To achieve this goal, the network was treated as a graph. Thus, concepts and algorithms from Graph Theory were used, like all cycles and paths. This paradigma made it possible to generate a set of inputs for data analysis. The application of the methodology in the Brazilian Altimetric Network – RAAP – showed consistente results, as long as the network has suficiente redundancy to allow detection and confirmation of possible temporal movements.