How To Fix Hypersonic 2 Error
Lourdes Vandewerker
I am receiving the following error when starting JBoss4:
Starting failed jboss:database=localDB,service=Hypersonic
java.sql.SQLException: General error: java.lang.NullPointerException
I am running the application under Eclipse, using the JBoss4 server.
The applications continue to run fine, however.
I had this problem once before, and I found a search entry which described fixing the problem by deleting an apparently corrupted file and then restarting the Application, which recreated the file correctly: this fixed the problem.
As I remember, it was somehow related to ColdFusion (I have both ColdFusion and Java apps running under the same JBoss4 server), but I could be wrong. No rap on ColdFusion, which is a nice product, just that I think it may be related.
However, I can't find the search entry anymore.
Can anybody help, please?
Aims. Bow shock waves are a common feature of groups and clusters of galaxies since they are generated as a result of supersonic motion of galaxies through the intergalactic medium. The goal of this work is to present an analytical solution technique for such astrophysical hypersonic blunt body problems.
The analysis developed by Schneider (1968) allows a very elegant treatment of the inviscid hypersonic blunt body problem. It is an inverse method, which means that the shock wave shape is assumed, and both the body shape, which supports the assumed shock, and the flow field between shock and body (i.e. the shock layer) are calculated. The fundamental advantage of this method over the ones by other authors is its uniform validity in the whole flow field (from the stagnation region up to large distances from the projectile nose). Until now this method has been adopted in aerospace engineering, in particular for solving the reentry problem of space probes, space shuttles, etc., in planetary or terrestrial atmosphere. However, to the best of our knowledge, this paper demonstrates its first application to an astrophysical problem.
In the astrophysical context, the case of a perfect gas with constant specific heats is of great interest. The inverse compression ratio is then given by (see e.g. Landau & Lifshitz 1987) (32)We point out that an analogous relation is valid for , if all asterisks in Eq. (32) are replaced by hats.
Finally, it should be noted that the astrophysical possibility of this analytical method is hardly restricted to galaxy-IGM interaction alone; on the contrary, any scenario, such as bow shocks around subclusters, gas bullets, jets (Herbig-Haro objects) or individual stars can be covered with it as well.
This paper presented an analytical solution technique for the inviscid hypersonic blunt body problem and applied it for the first time to the interaction between galaxies and the IGM. The method follows an inverse approach, which means that the shape of the bow shock has to be parametrized to be consistent with the galaxy shape. Such an inverse approach has no substantial disadvantage in the view of the fact that at high impact velocities the shape of the bow shock becomes similar to the shape of the body. For lower Mach numbers we find that the problem can be solved iteratively. First, we assumed the geometric form of the bow shock, then analytically derived the shape of the galaxy, and compared it to the relevant parameters (e.g. axes ratio, dimensions). In the next step, the bow shock curve was changed, and the body shape recalculated until convergence was obtained. In all cases we tested, this was achieved fairly rapidly. The solution, which is valid in the whole flow field, and in particular takes velocity gradients into account along streamlines, is based on two main assumptions; first, the density ratio across the shock has to be large, and, second, the pressure at a point Q (Fig. 1) of the disturbed flow field must not to be very small in comparison to the pressure immediately behind the shock in the intersection point of the shock surface with its normal through Q. In our derivation, heat conduction, viscosity, as well as terms of the order of χ (density ratio) are neglected. It should be stressed that it is not required that the shock layer, which is the area between the bow shock wave and the projectile, has to be thin. The presented treatment thus surpasses in sophistication methods like the analytic solution for the thin-shell problem of a hypersonic wind interacting with a rigid sphere by Cant & Raga (1998) and allows astrophysical problems that involve bow shocks generated by a hypersonic flow to be tackled more realistically.
It is a pleasure to thank Wilhelm Schneider for helpful discussions and Ian R. Stevens for providing essential parts of the used radiative cooling algorithm. Use of VH-1, developed by the numerical astrophysics group at the University of Virginia ( -1), is hereby acknowledged. We also thank the anonymous referee for his/her constructive suggestions which helped to improve the paper. The calculations were performed on the computers of the Institute for Astronomy, University of Vienna (Austria).
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SQL Injection is a severe security vulnerability that allows attackers to manipulate an application's database by injecting malicious SQL code. If not addressed, it can lead to unauthorized access, data breaches, and data manipulation. In this step-by-step manual, we will focus on fixing the SQL Injection vulnerability in a web application that uses the Hypersonic SQL (HSQL) database.
Before fixing the vulnerability, it's essential to understand the code that is susceptible to SQL Injection. Typically, SQL Injection occurs when user-supplied data is concatenated directly into SQL queries without proper validation or parameterization. Look for code snippets that construct SQL queries like this:
Conclusion:
Fixing the SQL Injection vulnerability in a web application using Hypersonic SQL involves understanding vulnerable code, adopting Prepared Statements, validating and sanitizing user input, following the least privilege principle, implementing proper error handling, and considering additional security measures like a WAF. By following these steps and maintaining a security-first mindset, you can significantly reduce the risk of SQL Injection and enhance the overall security of your web application.
The Missile Defense Agency (MDA) and Space Development Agency (SDA) are currently developing elements of a hypersonic missile defense system to defend against hypersonic weapons and other emerging missile threats. These elements include the tracking and transport layers of the Proliferated Warfighter Space Architecture (PWSA) and various interceptor programs. As MDA and SDA continue to develop these systems, Congress may consider implications for oversight and defense authorizations and appropriations.
Hypersonic weapons, like ballistic missiles, fly at speeds of at least Mach 5, or roughly 1 mile per second. Unlike ballistic missiles, hypersonic weapons do not follow a ballistic trajectory and can maneuver en route to their target. Russia reportedly fielded its first hypersonic weapons in December 2019, while some experts believe that China fielded hypersonic weapons as early as 2020. The United States does not have any fielded hypersonic weapons.
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When spacecraft return to Earth, one of the tensest parts of the mission is the radio black out that occurs as the vehicle re-enters the atmosphere. Travelling at hypersonic speeds of between Mach 8 and 15, the spacecraft heats and breaks down molecules in the atmosphere causing a plasma to form. It is this plasma sheath that prevents radio communication.
Over the years, numerous groups have studied various ways around this problem. One idea is to use low frequency signals that are not blocked by the plasma. However, these provide only low data rates.
Another is to shape the craft so that the plasma does not form in certain areas where a radio antenna can be placed. But this means the entire vehicle has to be designed around the communications system, which then cannot be changed.
First some background. Plasmas absorb electromagnetic waves close to a special resonant frequency called the plasma frequency, which depends on the properties of the plasma itself such as its density.
Korotkevich and co point out that any incoming signal close to this frequency is both reflected and absorbed by the plasma. The reflected signal is lost but the absorbed energy sets up a resonating electric field at a certain depth with the plasma.
The new idea is to zap this layer with radio waves generated from within the spacecraft. These waves will be both absorbed by the plasma and reflected back inside the spacecraft. However, the key point is that the reflected waves ought to be modulated by any changes in the electric field within the plasma.
There are some caveats, of course. Wile the study they publish today is interesting, it considers only an idealised case and numerous extra details will need to be taken into account to get a prototype working.
Of course, the big interest is likely to come from the military. While the radio black-out is little more than an irritant for human missions, it is a serious limitation for military craft such as ballistic missiles or hypersonic planes. Radio black out prevents these vehicles from accessing GPS signals for navigation and does not allow them to be re-targeted or disarmed at the last minute.
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