25,734 research outputs found
Effect of differing forages on the early growth and behaviour development of dairy heifers during pre- and post weaning periods : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand
The objective of this study was to evaluate the effects of different forage diets fed to young calves on early growth, behaviour development and long term milk performance. In experiment 1, 60 calves were randomly allocated to one of three diets, fed starter diet with no forage (PS), PS with additional moist alfalfa (PSA) or PS with additional pasture hay (PSH). In experiment 2, 108 calves were randomly allocated to one of three diets, PSH, PS with low (LF) or high (HF) moist alfalfa based total mixed rations. In Experiment 1, greater dry matter intake and liveweights were observed in PSH followed by PSA and then PS during the pre- and post-weaning periods. Longer time eating and ruminating behaviours were observed in PSA and PSH than PS during pre- and post-weaning periods. In Experiment 2, greater dry matter intake and liveweights were observed in PSH than LF and HF diets during the pre- and post-weaning periods. Greater numbers of incidents of allo-grooming were observed in the HF and PSH diets and calves spent longer time eating than LF calves. During post-weaning period, HF and PSH fed calves spent more time lying than LF fed calves. After turning out to pasture, no behaviour differences were observed among treatments in both experiments. While monitoring long term performance, no differences were observed in animals from Experiment 1 in terms of liveweight, milk yield, protein or fat production. From Experiment 2, greater liveweight gains were observed in HF and PSH fed animals than LF fed animals till first lactation. During first lactation, greater milk yield was observed in HF fed animals than PSH or LF fed animals. Greater fat production was observed in LF fed animals than HF or PSH fed animals during third lactation. The effects of diets on the long term performance of the animals should be repeated with sufficient animal numbers per treatment
Flashover performance of lightning protected buildings using scaled models and electric field analysis
In early era, Benjamin Franklin discovered that the application of Lightning Rod (also known as the Franklin Rod) method is found to be effectived as a lightning protective device for buildings. Hence, it was considered among the best solution to overcome the problems facing by publics due to lightning strikes. However, few years later it was found that the corroded Franklin Rod due to the impact of environmental contaminations tends to reduce its ability to effectively capture the lightning strikes. The directly or indirectly impacts of lightning strikes had caused owners to spend huge amount of money just to repair damages on the buildings. Nowadays, there were many professional standards and documents guiding public to properly install the building’s lightning protection system, yet the same damages problems had shown to be frequently occur that related to the strikes often bypasses the of Lightning Air Terminal (LAT) system. The main reason for this could be due to lacking ideas by learned circle of lightning experts as not to fully understand the behavior of Franklin Rods system when it interacts with the lightning leaders. Therefore, this thesis discusses the works that investigated the flashover performances occurred on the buildings with various structural geometry shapes. The case study method is using small scaled models for both laboratory and simulation works, aiming to understand the Franklin Rods performance on capturing lightning leaders. Summarizing the works, about 11 scaled-down building shape models equipped with Franklin Rods system are selected in the case studies such as follows; a conical, gable, triangular, half circle, L-shape, square, cylindrical, butterfly, pyramid, rectangular and inclined like shapes. These models were then injected with 30 lightning flashes each using the 100 kVpeak single stage impulse generator. This number of flashes is considered as total two-years lightning activity frequencies in Malaysia, which the lighting flash density is statistically recorded to be around 15 flashes / year / km2. The maximum applied voltage is about 86.5 kVpeak. The model scaling concept is based on 1:30 cm ratio for every 3 m height of building structure. Interestingly, the overall work data had shown that the pyramid-like shapes is found to be the best structure type to be used in reducing the LAT bypasses and direct strike damages. The structure’s Franklin Rod protection system captured the least number of strikes during competitive tests conducted on all of the scaled down building models. Works of electric field analysis on all building models were conducted using ANSYS Maxwell simulation tool. Utilisation of electric field plot data in this work enables the creation of likelihood factor (ranging from 0.1 to 0.9) method that so useful to capable predict the strikes pattern occurring on dedicated terminal rod. Both laboratory and simulation work also confirm that the edge shapes play crucial roles as intense electric fields is found to accumulate on the edges area when the Franklin Rod intercepts the lightning leaders. These mentioned findings lead to introducing better method of LAT placement on the top of the building, whereby the existing lightning protection system is recommended to have one of installed LAT rods elongated to act as sacrificial point to directly attract lightning strikes. All the work and key findings in this work can contribute to the science and technology field toward having a better LAT lightning protection system and also lead to better decision in selecting / designing the shapes and edges concept as to reduce likelihood of LAT bypasses and damages of the building structure
The Novel Coronavirus Outbreak: a Challenge Beyond Borders
Coronaviruses infect mammals and birds worldwide, and some of these viruses infect humans to cause mild to moderate lower-respiratory tract illnesses and rarely a severe illness. Like other viruses, coronaviruses evolved (change their genetic material and protein structure) and spread from animals to humans. The world has witnessed coronavirus evolving into severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012. Other recent examples include Dengue, Ebola, Chikungunya, Influenza and Zika virus outbreaks. It may or may not be relevant to note that first cases of both SARS-CoV in 2003 avian influenza virus (H5N1) in 1997 were isolated and identified at the same hospital in Hong Kong where the first case of the current outbreak of the Wuhan coronavirus has been identified. The new virus has been named as the Novel coronavirus (2019 nCoV)
A Study of IEEE 802.15.4 Security Framework for Wireless Body Area Network
A Wireless Body Area Network (WBAN) is a collection of low-power and
lightweight wireless sensor nodes that are used to monitor the human body
functions and the surrounding environment. It supports a number of innovative
and interesting applications, including ubiquitous healthcare and Consumer
Electronics (CE) applications. Since WBAN nodes are used to collect sensitive
(life-critical) information and may operate in hostile environments, they
require strict security mechanisms to prevent malicious interaction with the
system. In this paper, we first highlight major security requirements and
Denial of Service (DoS) attacks in WBAN at Physical, Medium Access Control
(MAC), Network, and Transport layers. Then we discuss the IEEE 802.15.4
security framework and identify the security vulnerabilities and major attacks
in the context of WBAN. Different types of attacks on the Contention Access
Period (CAP) and Contention Free Period (CFP) parts of the superframe are
analyzed and discussed. It is observed that a smart attacker can successfully
corrupt an increasing number of GTS slots in the CFP period and can
considerably affect the Quality of Service (QoS) in WBAN (since most of the
data is carried in CFP period). As we increase the number of smart attackers
the corrupted GTS slots are eventually increased, which prevents the legitimate
nodes to utilize the bandwidth efficiently. This means that the direct
adaptation of IEEE 802.15.4 security framework for WBAN is not totally secure
for certain WBAN applications. New solutions are required to integrate high
level security in WBAN.Comment: 14 pages, 7 figures, 2 table
Dentrification potential of different landuse types in an agricultural watershed, lower Mississippi valley.
Expansion of agricultural land and excessive nitrogen (N) fertilizer use in the Mississippi River watershed has resulted in a three-fold increase in the nitrate load of the river since the early 1950s. One way to reduce this nitrate load is to restore wetlands at suitable locations between croplands and receiving waters to remove run-off nitrate through previous termdenitrification.next term This research investigated previous termdenitrificationnext term potential (DP) of different land uses and its controlling factors in an agricultural watershed in the lower Mississippi valley (previous termLMV)next term to help identify sites with high DP for reducing run-off nitrate. Soil samples collected from seven land-use types of an agricultural watershed during spring, summer, fall and winter were incubated in the laboratory for DP determination. Low-elevation clay soils in wetlands exhibited 6.3 and 2.5 times greater DP compared to high-elevation silt loam and low-elevation clay soils in croplands, respectively. DP of vegetated-ditches was 1.3 and 4.2 times that of un-vegetated ditches and cultivated soils, respectively. Soil carbon and nitrogen availability, bulk density, and soil moisture significantly affected DP. These factors were significantly influenced in turn by landscape position and land-use type of the watershed. It is evident from these results that low-elevation, fine-textured soils under natural wetlands are the best locations for mediating nitrate loss from agricultural watersheds in the previous termLMV.next term Landscape position and land-use types can be used as indices for the assessment/modeling of previous termdenitrificationnext term potential and identification of sites for restoration for nitrate removal in agricultural watersheds
- …