Category Archives: Technology

Nanoscale control of desalination membranes could lead to cheaper water filtration

After a stint at a park last year in which it reminded visitors on safe distancing, Spot the robot dog has a new assignment – helping to do laser scans of structures built at worksites and sending the results over 5G for checks.

The four-legged Boston Dynamics machine’s new line of work is being tested by the Building and Construction Authority (BCA) and construction firm Gammon as part of several 5G applications the Government is trialling in Sentosa.

The 5G @ Sentosa project was launched by the Government Technology Agency (GovTech) on Tuesday (Oct 19). The aim is to roll out the successful Sentosa 5G trials to the mainland in the next five years.

Using 5G, the worksite scans made by the laser scanner equipped on Spot can be sent almost instantly, without lag, to building supervisors located elsewhere to check if the structures there are built according to their intended designs.

This is done by comparing the scan data with 3D models created earlier of what the completed structures should look like.

Such remote checking is useful during the Covid-19 pandemic if there are restrictions on people moving around worksites, for example.

Previously, the scans were done manually, which was resource-intensive and time-consuming. The scan data is also too large to be sent over the air through 4G.

But Spot, which was deployed at the Bishan-Ang Mo Kio Park in a pilot as a safe distancing robot in May last year, can be programmed to tirelessly scan worksites on its own.

Spot robot patrolling Bishan-Ang Mo Kio Park | The Straits Times

The robot canine’s work could also be extended to track the progress of and do quality control checks on construction projects. An alternative to Spot is a wheeled robot that performs a similar function.

Another project being tested by BCA and Gammon involves guiding worksite staff and helping them to better visualise installation works at a construction site using augmented reality.

Just How Big Was the Devastating 2020 Beirut Explosion?

On August 4, 2020, one of the largest non-nuclear explosions in history pulverized a Beirut port and damaged more than half the city. The explosion resulted from the detonation of tons of ammonium nitrate, a combustible chemical compound commonly used in agriculture as a high-nitrate fertilizer, but which can also be used to manufacture explosives.

Since that time, the explosive yield estimates varied widely, and in some cases, were inconsistent with what would be expected based on the amount of ammonium nitrate stored at the Beirut harbor. In addition, the crater size, seismic magnitude and mushroom cloud height seemed to be inconsistent.

Lawrence Livermore National Laboratory (LLNL) physicist Peter Goldstein has studied how water saturation of the explosive, ground and possibly water and debris from the near-source environment can help reconcile differences in the yield estimates obtained using these different measurements. Official records indicate that roughly 2.7 kilotons of explosive material were stored at the Beirut harbor warehouse where the explosion occurred. The detonation of these materials resulted in a large crater and seismic measurements suggested it was possible that the yield was at least a few kilotons and possibly much greater. However, there were other estimates that suggested the yield was quite a bit smaller, possibly as little as half a kiloton.

Goldstein’s research, which appears in Countering WMD Journal, analyzes the crater dimensions, seismic magnitude estimates and the cloud height of the explosion and shows that all the data are consistent with a yield of around a kiloton when water/saturation is accounted for. “Water in the near-source environment can have a significant effect on many observations, including crater formation, cloud rise, seismic magnitudes and blast wave effects,” he said.

Goldstein used crater-size observations from satellite imagery and empirical data for scaled crater radii from past chemical and nuclear explosions to estimate the yield.

“The evidence suggests that the relatively large crater radius is due to a high degree of saturation of the ground beneath the explosion. It is likely that this saturation increased coupling of shock wave energy to the surrounding material and reduced the effective stress/strength of the material,” he said.

He also found that yield estimates based on seismic body-wave magnitude, the maximum debris cloud height and the observed crater depth corroborated the estimates based on crater radius.

Confidence in the reliability of these models is critical for emergency response planning to mitigate potential consequences from accidents such as the Beirut explosion or deliberate acts that could involve improvised nuclear devices or radioactive dispersal devices.

This research also is relevant to nuclear explosions. It suggests that features of the near-source environment can have a large effect on shock/blast waves, seismic motions and crater formation, as well as cloud rise and fallout effects. The effects also propagate into things like the yield estimate. Goldstein said he expects near-source features like water to have a significant effect on other explosion phenomena, including radiation transport and post-detonation debris formation.

The Sun and Stars Affect Our Everyday Clouds and, Ultimately, Earth’s Energy Budget

This is the result of a new study by researchers from DTU Space at the Technical University of Denmark (DTU) and of The Hebrew University of Jerusalem, who have traced the consequences of eruptions on the Sun on clouds and Earth’s energy balance.

“We tested cosmic ray effects on the atmosphere for about two weeks. When solar explosions reduce the cosmic ray flux reaching Earth, they temporarily reduce the production of small aerosols. The aerosols are molecular clusters in the air that normally grow to seed the water droplets of low-level clouds. This, in turn, reduces the cloud cover, which is known to affect climate,” says senior researcher. Henrik Svensmark, lead author of the study published in Nature’s Scientific Reports.

The breakthrough is that the effect on the Earth’s energy budget has been quantified directly using detailed satellite observations from the CERES instrument on NASA’s Terra and Aqua satellites. The observation is that Earth absorbs almost 2 W/m2 extra energy within 4 to 6 days of the cosmic-ray minimum.

This research, in which Jacob Svensmark, Martin Bødker Enghoff, and Nir Shaviv participated, connects observable variations in clouds and Earth’s energy budget to Danish laboratory experiments and theory. It shows how cosmic rays help make the all-important aerosols and accelerate their growth to cloud condensation nuclei.

Previous research by the team predicted that the effects should be most noticeable in low altitude liquid clouds over the oceans is confirmed with the new study. Spatial maps verify that the dominating net radiative forcing changes are from low liquid clouds over the pristine seas.

“We now have simultaneous observations of decreases cosmic rays, aerosols, clouds, and the energy budget, which is quite amazing,” adds professor Nir Shaviv.

“The solar effects in this study are too short-lived to have a lasting effect on the climate. They do, however, dramatize the cosmic ray-cloud mechanism that works more patiently on longer time scales. The hope is that this result will help rethink the long-term effect of solar activity and cosmic rays on climate,” Says Henrik Svensmark.

Uk scientists to produce low cost high performance ventilators

This is done by having staff wear headsets with visors and superimposing digital models of structures to be installed over what employees see at the worksite in person.

The digital overlay allows users to align actual structures at the worksite more accurately during their installation.

This operation needs very low latency and high bandwidth to stream the overlays accurately in real time, which 5G can support. Current 4G networks are not suitable for this.

Using the digital overlay has safety benefits too, as it also allows worksite staff to do a digital rehearsal of an installation before it actually happens, so any issues that surface can be identified early.

5G is also being tested by the National Environment Agency and Nanyang Technological University (NTU) to remotely control a driverless road sweeper in Sentosa during an emergency.

[WATCH] A remote-controlled roadsweeper vehicle on Sentosa

MORE ON THIS TOPIC
First S’pore Govt 5G trials in Sentosa, like remote-controlled roadsweeper tests, launched
Tests have shown that the vehicle can be operated from NTU, which is about 20km from Sentosa.

The teleoperation system that an operator uses to control the road sweeper looks like a driving simulator and creates the illusion that he is sitting in the actual vehicle in Sentosa, as it receives data such as videos and sounds sent over 5G from the sweeper’s sensors.

So, when he helps to navigate, such as when the vehicle encounters tricky road or weather conditions, he can react quickly since he can see the area in front of the road sweeper, hear sounds near it and even feel it going over humps on the road.