Research

2518 KiB

Open AccessArticle

Path Loss Measurements of Indoor LTE System for the Internet of Things

by Guan-Yi Liu, Tsung-Yu Chang, Yung-Chun Chiang, Po-Chiang Lin and Jeich Mar

Appl. Sci. 2017, 7(6), 537; https://doi.org/10.3390/app7060537 - 23 May 2017

Cited by 13 | Viewed by 5444

The Internet of Things (IoT) provides communication service for future smart manufacturing, which is capable of independently exchanging and responding to information to manage industrial production processes. For the purpose of connecting machines, devices, sensors, and people with each other in a factory, [...] Read more.

The Internet of Things (IoT) provides communication service for future smart manufacturing, which is capable of independently exchanging and responding to information to manage industrial production processes. For the purpose of connecting machines, devices, sensors, and people with each other in a factory, reliable and scalable communication networks used in the cellular IoT are of great importance. This paper aims at channel parameter measurements of indoor Long Term Evolution systems in order to achieve good coverage and service reliability (SR) for the IoT. For the purpose of determining the path loss exponent and the standard deviation of the received shadow fading signal, we use software defined radio techniques to build a small cell experimental platform which contains an evolved node B and user equipment. Received power measurements were performed on this platform. Finally, based on the experimental results, the modified path loss model and the calculated fade margin (FM) for 90% SR are exploited to predict the coverage range of the small cell base station deployed in the factory. The measured path loss channel models are compared with International Telecommunication Union (ITU) path loss channel model. Full article

(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Advanced Manufacturing (ICAM 2016))

► Show Figures

Figure 1

1479 KiB

Open AccessArticle

Performance of Nanostructures within InGaN-Based Multiquantum-Well Light-Emitting Devices

by Ya-Fen Wu and Jiunn-Chyi Lee

Appl. Sci. 2017, 7(4), 380; https://doi.org/10.3390/app7040380 - 11 Apr 2017

Cited by 1 | Viewed by 3118

Abstract

We introduced multiquantum-barrier (MQB) nanostructures into the barrier layers of InGaN/GaN multiquantum-well (MQW) heterostructures to improve the operation characteristics of the light-emitting devices. The electroluminescence (EL) spectra were examined over a broad range of temperatures for the samples. We observed inhibited carrier leakage [...] Read more.

We introduced multiquantum-barrier (MQB) nanostructures into the barrier layers of InGaN/GaN multiquantum-well (MQW) heterostructures to improve the operation characteristics of the light-emitting devices. The electroluminescence (EL) spectra were examined over a broad range of temperatures for the samples. We observed inhibited carrier leakage for the sample with the MQB nanostructures. Greater inhomogeneity of nanocrystallite size and a stronger localization effect were also observed for the sample. To interpret this phenomenon, high-resolution X-ray diffraction curves were measured and analyzed using the Warren–Averbach model. External quantum efficiency as a function of temperature was also evaluated. The calculation results correspond with the inference the EL measurements provided. We determined that the performance of the light-emitting devices is enhanced by the MQB nanostructures within InGaN/GaN MQWs. Full article

(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Advanced Manufacturing (ICAM 2016))

► Show Figures

Figure 1

2252 KiB

Open AccessArticle

Grain Size in Aluminum Alloy 6061 under Hot Ring Compression Test and after T6 Temper

by Kuang-Jau Fann and Chun-Chi Chen

Appl. Sci. 2017, 7(4), 372; https://doi.org/10.3390/app7040372 - 08 Apr 2017

Cited by 5 | Viewed by 7437

Abstract

Peripheral coarse grain during and after hot forming is often a major inconvenience for manufacturing aluminum alloy parts. Not only is the strength reduced, but the subsequent surface treatments are also hard to realize. The literature has shown that peripheral coarse grain is [...] Read more.

Peripheral coarse grain during and after hot forming is often a major inconvenience for manufacturing aluminum alloy parts. Not only is the strength reduced, but the subsequent surface treatments are also hard to realize. The literature has shown that peripheral coarse grain is very likely induced by the previous process, such as extrusion. To investigate if peripheral coarse grain could be caused solely by hot forming, this study removed the billet surface layers. This eliminates the effect from the previous processes preparing the billets and forms ring specimens for executing ring compression test. The ring compression test can reveal the friction circumstance of the specimen to the die surface and create versatile deformation in the specimens to simulate forging situations, thereby providing multifaceted conditions to develop diverse grain size in specimen, particularly on its surface. The experiments were designed and analyzed under the Taguchi method, with consideration for factors such as working temperature, speed and amount of compression, and lubricant. Under each experiment, no peripheral coarse grains were found in the specimen, which were peeled and compressed, and even the average grain size after compression test is larger than that of the received billet. No peripheral coarse grains were found in the subsequent T6 temper either, which could, however, refine the grains. Full article

(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Advanced Manufacturing (ICAM 2016))

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Selected Papers from the 2016 International Conference on Advanced Manufacturing (ICAM 2016)

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (3 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI